JOIN THE IN-PERSON EVENT IN SAN DIEGO, CALIFORNIA
1 - 5 August 2021
For years the spin degree of freedom has been directly used as an information support in nanometer-scale devices. Today applications mostly concern the huge market of information storage, read heads, nonvolatile magnetic memories (MRAMs), or magnetic logic units. Recent developments are being considered for spin-based logic or quantum computing. New topics are emerging in frontier fields, e.g. topological spin structures, topological insulators, Majorana fermions, antiferromagnetic spintronics, spin photonics and spin optics, ultra-fast phenomena and THz emission or spin-caloric phenomena. These advances make use of the fascinating developments of new materials.

The purpose of the conference is to provide a broad overview of the state-of-the-art and perspectives, bringing together experts from different communities: fundamental physics (experimental and theoretical), materials science and chemistry, fabrication processes and industrial developments, etc. Contributions for this conference are encouraged in particular in the following areas: ;
In progress – view active session
Conference 11805

Spintronics XIV

In person: 1 - 2 August 2021Conv. Ctr. Room 2
On demand starting 1 August 2021
View Session ∨
  • 1: Spin Hall Effect I
  • 2: Spin Hall Effect II
  • 3: Spincaloritronics and Magnonics
  • 4: Superconductivity I
  • 5: Superconductivity II
  • 6: Magnetic Inertia and Nutation
  • 7: Ultra-Fast and THz Spintronics
  • 8: Ultra-Fast Spintronics and Magnetoplasmonics
  • 9: Antiferromagnetic Spintronics
  • 10: Spin Lasers I
  • 12: Magnetism and Chirality I
  • 11: Spin Lasers II
  • 13: Magnetism and Chirality II
  • 14: Spin Logic and Devices
  • Nanoscience + Engineering Plenary Session
  • Nanoscience + Engineering Plenary Networking Event
  • 15: Spin Sensors
  • 16: Neuromorphic Computing
  • 17: Spin Decoherence
  • 18: Semiconductor Spintronics
  • 19: Semiconductor Spintronics and Valleytronics
  • 20: Tunneling Phenomena
  • 21: Artificial Spin-Ice and Spin Textures
  • 22: New Materials, Structures, and Systems
  • Live Remote Keynote Session: Nanoscience + Engineering Applications I
  • Live Remote Keynote Session: Nanoscience + Engineering Applications II
2021-07-24T16:24:05-07:00
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UPCOMING LIVE EVENTS:
Session 1: Spin Hall Effect I
11805-1
Author(s): Jian Liu, Hunan Univ. (China); Junxiao Zhou, Hunan Univ. (China), Univ. of California (United States); Hailu Luo, Weixing Shu, Shuangchun Wen, Hunan Univ. (China)
On demand starting 1 August 2021
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In the previous works the spin Hall effect (SHE) of light was usually detected by the quantum weak measurement technique in which the complete information of the field was lost. In this work, we investigate the spatial evolution of the whole field in the SHE of light on reflection. First, we establish a model to describe the polarization state of reflected light and disclose its relationship with the SHE. Then, it is found that the reflected polarization generally becomes a vector field. The SHE due to the polarization gradient is manifested as a spin-dependent splitting. Further, it is found that both the incident angle and the incident polarization can affect the polarization of reflected light noticeably. Finally, the evolution of the energy flow is analyzed to disclose the underlying physical mechanism.
11805-2
Author(s): Takeshi Seki, Hiroto Masuda, Koki Takanashi, Tohoku Univ. (Japan)
On demand starting 1 August 2021
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A promising way for the conversion from charge current to spin current is to exploit the spin Hall effect (SHE). Aside from the usage of elemental nonmagnetic materials, element doping or alloying is a promising way to develop a spin Hall material. In order to reveal the optimum composition for achieving the large SHE in the Cu-Ir binary alloys, we exploited the high-throughput combinatorial technique based on spin Peltier imaging. They discovered that the non-equilibrium Cu-Ir alloys beyond the solubility limit are candidates to achieve the large SHE, in which a large spin-Hall angle of ~ 6% was obtained for Cu76Ir24. In addition to the aspect from SHE, we also found that Cu-Ir is a nonmagnetic spacer layer material allowing us to realize moderately strong antiferromagnetic coupling (AFC) between two ferromagnetic layers separately by Cu-Ir. The simultaneous achievement of AFC and SHE makes the Cu-Ir an useful material for antiferromagnetic spintronics.
11805-3
Author(s): Sachin Krishnia, Fernando Ajejas, Yanis Sassi, Sophie Collin, Albert Fert, Jean-Marie George, Nicolas Reyren, Vincent Cros, Henri Jaffrès, Unité Mixte de Physique CNRS/Thales (France)
On demand starting 1 August 2021
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Spin-orbit torques (SOTs) allow controlling the magnetization of diverse classes of magnetic multilayers and devices. The mechanism utilizes spin-orbit interactions such as spin Hall effect in heavy metals and/or Rashba effect at ferromagnetic/heavy-metal interface with broken inversion symmetry. The SOTs have damping-like (HDL) and field-like (HFL) effective field components. In this talk, we will present the mechanism of spin-transport in ultrathin magnetic multilayer whose thicknesses span across the characteristic spin-dephasing length, and how it results in HDL and HFL nearby the crossing point of this specific length. To this aim, we have quantified SOTs in a series of samples Pt 8|Co x|Al 1.4|Pt 3 with x = 0.55, 0.7, 0.9, 1.2, 1.4 nm. Our experiments demonstrate the presence of very large field-like torque arising from Co|Al interface for Co thickness smaller than spin-dephasing length. The results suggest the contribution of additional mechanisms of spin-current generation.
11805-4
Author(s): Maxen Cosset-Cheneau, Spintec (France); Sara Varotto, Unité Mixte de Physique CNRS/Thales (France); Paul Noël, ETH Zurich (Switzerland); Cécile Grèzes, Van Tuong Pham, Yu Fu, Patrick Warin, Ariel P. Brenac, Vincent Baltz, Alain Marty, Spintec (France); Serge Gambarelli, Jean-François Jacquot, SyMMES (France); Daria Gusakova, Spintec (France); Xavier Waintal, Pheliqs (France); Henri Jaffrès, Unité Mixte de Physique CNRS/Thales (France); Jean-Philippe Attané, Laurent Vila, Spintec (France)
On demand starting 1 August 2021
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The link between magnetization and Spin Hall Effect (SHE) has remained mostly unclear for now. In a first part of this contribution, we study oh the presence of the magnetization affect the SHE, by performing in the weak ferromagnet NiCu Spin Pumping-FMR measurements across the ferromagnetic / paramagnetic critical temperature. We show that the high spin Hall effects which can be obtained in 3d ferromagnets seems to be independent of the magnetic phase. In a second part, we show that the spin absorption process in a ferromagnetic material depends on the spin orientation relative to the magnetization. Using a ferromagnet to absorb the pure spin current created within a lateral spin valve, we evidence and quantify a sizable orientation dependence of the spin absorption in Co, CoFe, and NiFe. These experiments allow us to determine the spin-mixing conductance, an elusive but fundamental parameter of the spin-dependent transport.
Session 2: Spin Hall Effect II
In person: 1 August 2021 • 1:30 PM - 2:00 PM PDT | Conv. Ctr. Room 2
11805-7
Author(s): Olaf Van T Erve, Connie H. Li, Berry T. Jonker, U.S. Naval Research Lab. (United States)
In person: 1 August 2021 • 1:30 PM - 2:00 PM PDT | Conv. Ctr. Room 2
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The spin mixing conductance is an important figure of merit for spin transport across an interface. This is a particularly important number for Spin Orbit Torque Magnetic Random Access Devices, where spin generated in one layer is used to provide the spin torque needed to flip the magnetization in an adjacent layer. Here the spins are generated in either an topological insulator (TI) or an heavy metal (HM). The overall efficiency of such a device depends on both the charge to spin conversion in the spin generation layer and the spin mixing conductance of the interface.
11805-6
Author(s): Anna Semisalova, Tanja Strusch, Univ. Duisburg-Essen (Germany); Kay Potzger, Kilian Lenz, Rantej Bali, Jonathan Ehrler, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Ralf Meckenstock, Univ. Duisburg-Essen (Germany); Jürgen Lindner, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Michael Farle, Univ. Duisburg-Essen (Germany)
On demand starting 1 August 2021
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We report on ferromagnetic resonance (FMR) detected spin pumping in Fe60Al40 /Pd and Py/Fe60Al40 bilayers, and laterally patterned Fe60Al40 (FeAl) nanostructures. The magnetic properties of FeAl alloy are tailorable from paramagnetic to ferromagnetic state by variation of the structure through an ion beam irradiation, which makes this material promising for the fabrication of magnetic landscapes and magnonic crystals. Exploiting this tunability, we show that FeAl can be used as spin source and spin sink in spin pumping experiments. Using the material with the identical chemical composition as para- and ferromagnet, we suggest a new pathway for creating lateral spin pumping geometries which are produced with ion beam irradiation of B2 alloys.
11805-8
Author(s): Dongwook Go, Forschungszentrum Jülich GmbH (Germany)
On demand starting 1 August 2021
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Spin-orbit torque is one of the key phenomena in modern spintronics, which enables electric control of magnetic moments. The mechanism of the spin-orbit torque is often interpreted in terms of the spin current generated by an electric field in the presence of spin-orbit coupling. However, the electron can carry angular momentum not only by spin but also by its orbital degrees of freedom. Quite often, orbital angular momentum current can be more efficiently generated by an electric current than the spin current since it does not require spin-orbit coupling. With this consideration, we recently proposed a mechanism of torque generation based on electronic orbital angular momentum current, which is now called orbital torque. In this talk, I will explain the background and idea of the orbital torque mechanism and provide guidelines for experimental observation.
11805-9
Author(s): Jean-Eric Wegrowe, Félix Faisant, Melvin Creff, Ecole Polytechnique (France)
On demand starting 1 August 2021
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We study the stationary state of Hall-bar devices composed of a load circuit connected to the lateral edges of a Hall-bar. We follow the approach developed in a previous work (Creff et al. J. Appl. Phys 2020) in which the stationary state of a ideal Hall bar is defined by the minimum power dissipation principle. The presence of both the lateral circuit and the magnetic field induces the injection of a current: the so-called Hall current. Analytical expressions for the longitudinal and the transverse currents are derived. The same analysis is performed on the spin-Hall effect, in the framework of the two spin-channel model.
11805-10
Author(s): Sara Varotto, Luca Nessi, Politecnico di Milano (Italy); Stefano Cecchi, Paul-Drude-Institut für Festkörperelektronik (Germany); Jagoda Slawinska, Univ. of North Texas (United States); Paul Noël, Univ. Grenoble Alpes (France), CNRS (France), CEA (France); Federico Fagiani, Matteo Cantoni, Politecnico di Milano (Italy); Marcio Costa, Univ. Federal Fluminense (Brazil); Raffaella Calarco, Paul-Drude-Institut für Festkörperelektronik (Germany); Marco Buongiorno Nardelli, Univ. of North Texas (United States); Manuel Bibes, Unité Mixte de Physique CNRS/Thales (France); Silvia Picozzi, Istituto Superconduttori, Materiali Innovativi e Dispositivi (Italy); Jean-Philippe Attané, Laurent Vila, Univ. Grenoble Alpes (France), CNRS (France), CEA (France); Riccardo Bertacco, Christian C. Rinaldi, Politecnico di Milano (Italy)
On demand starting 1 August 2021
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Since the 1980s, the generation and detection of spin currents has relied on ferromagnets. Their switching today relies on spin-orbit torque from heavy metals. Nevertheless, spin injection in semiconductors has rather low efficiency. Ferroelectric Rashba semiconductors (FERSC) [1,2] may constitute a new paradigm for semiconductor spintronics, thanks to the combination of semiconductivity, large spin-orbit interaction, and the non-volatility provided by ferroelectricity. Here we report the room-temperature ferroelectric switching of spin-to-charge conversion in epitaxial GeTe films. We first show that ferroelectricity in GeTe can be reversed by electrical gating despite its high carrier density. Then, we reveal a spin-to-charge conversion as effective as in Pt, but whose sign switches with the ferroelectric polarization. These results open a route towards devices combining spin-logic and memory integrated into a silicon-compatible material.
Session 3: Spincaloritronics and Magnonics
11805-13
Author(s): Igor Barsukov, Univ. of California, Riverside (United States)
On demand starting 1 August 2021
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We develop an approach for toggling magnon processes at nanoscale. We demonstrate an experimental proof-of-concept in magnetic tunnel junction nanodevices, consisting of a free layer and a synthetic antiferromagnet. By triggering the spin-flop transition in the synthetic antiferromagnet and utilizing its nonuniform dipole field, we controllably modify magnon interaction in the free layer. We achieve its tunability by at least one order of magnitude and realize two distinct dissipative states. The results open up an avenue for controlling magnon processes by external stimuli at nanoscale and show prospects for a variety of spin-torque applications, magnetic neural networks, and hybrid quantum information technologies. An immediate consequence of modified magnon interaction is nanomagnet's response to spin-torques. In particular, we show that degenerate resonant three-magnon process inverts an antidamping spin-torque into a torque that enhances dissipation. Supported by NSF-ECCS-1810541.
Session 4: Superconductivity I
11805-14
Author(s): Jason Robinson, Univ. of Cambridge (United Kingdom)
On demand starting 1 August 2021
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Spin currents are fundamental to spintronics, but in the normal state large charge currents are required at device inputs in order to generate sufficiently large output spin current densities. In this talk I will review our group’s discovery and progress in generating and controlling superconducting pure spin currents through the transfer of spin angular momentum via proximity-induced equal-spin triplet states in superconducting Nb. I will show that spin-orbit coupling (SOC) in conjunction with a magnetic exchange field generates spin-polarized triplet pairs. In particular, I will demonstrate that when a perpendicularly magnetized Pt/Co/Pt spin sink is proximity-coupled to superconducting Nb, ferromagnetic spin-pumping efficiency in the superconducting state is tunable by controlling the tilt angle of the Co layer magnetization, thus increasing the degree of orthogonality between the SOC and magnetic exchange field at the Nb/Pt/Co interfaces.
11805-15
Author(s): Alex Matos-Abiague, Joseph D. Pakizer, Wayne State Univ. (United States); Benedikt Scharf, Julius-Maximilians-Univ. Würzburg (Germany)
On demand starting 1 August 2021
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We theoretically investigate the crystalline anisotropy of topological superconductivity (TS) in phase controlled planar Josephson junctions (JJs) subjected to Rashba and Dresselhaus spin-orbit couplings and in-plane magnetic fields. We show how the interplay between the magnetic field direction and the orientation of the junction with respect to its crystallographic axes can affect the TS. Our results explain previous experiments demonstrating the high sensibility of TS to the in-plane magnetic field direction. The anisotropy can be used to electrically tune between BDI and D symmetry classes in a controlled fashion and thereby optimize the stability and localization of Majorana bound states in planar JJs. Our findings can be used as a guide for achieving the most favorable conditions when engineering TS in planar JJs and can be particularly relevant for setups containing non-collinear junctions, which have been proposed for fusion and braiding operations on multiple Majorana pairs.
11805-16
Author(s): Javad Shabani, New York Univ. (United States)
On demand starting 1 August 2021
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Recently there is a great deal of interest to understand and control the order parameter characterizing the collective state of electrons in quantum heterostructures. This is due to the fact that new physical behavior can emerge which is absent in the isolated constituent materials. With regards to superconductivity this has opened a whole new area of investigation in the form of topological superconductivity. Topological superconductors are expected to host Majorana fermions, electronic states with non-abelian statistics that can be used to realize topologically protected quantum information processing. In this talk, we present our progress in developing epitaxial semiconductor-superconductor heterostructures to host topological superconductivity. We find experimental transport and phase signatures consistent with topological superconductivity using external magnetic field in planar Josephson junctions. These signatures disappear in trivial superconductivity at zero magnetic field.
11805-17
Author(s): Taro Yamashita, Nagoya Univ. (Japan)
On demand starting 1 August 2021
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In recent years, various novel phenomena such as π-state (π-junction) and long-ranged supercurrents emerged in ferromagnetic Josephson junctions (superconductor/ferromagnet/superconductor junctions) have been studied so actively. An attractive device application of the ferromagnetic π-junction is a flux-bias-free superconducting flux quantum bit (qubit). By inserting the π-junction in the superconducting loop of the flux qubit, an external flux bias corresponding to half flux quantum, which is required for the operation of the conventional flux qubits, becomes unnecessary. This flux-bias-free feature is a great advantage in the realization of large-scale quantum circuits with many qubits. In the talk, we will present recent progress on the development of NbN-based ferromagnetic Josephson junctions which is suitable for the quantum circuits. We also show the experimental results on the several types of the quantum circuits with the NbN-based ferromagnetic π-junction.
Session 5: Superconductivity II
11805-19
Author(s): Tong Zhou, Univ. at Buffalo (United States); Matthieu C. Dartiailh, Kasra Sardashti, New York Univ. (United States); Jong E. Han, Univ. at Buffalo (United States); Alex Matos-Abiague, Wayne State Univ. (United States); Javad Shabani, New York Univ. (United States); Igor Zutic, Univ. at Buffalo (United States)
On demand starting 1 August 2021
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With non-Abelian statistics and nonlocal degrees of freedom, Majorana bound states (MBS) are suitable for implementing fault-tolerant topological quantum computing. While the main efforts to realize MBS have focused on one-dimensional systems, it requires delicate parameter tuning and its geometric constraints pose significant challenges for the demonstration of non-Abelian statistics. Building on recent experimental advances in planar Josephson junctions (JJs), we propose how to overcome this obstacle in topological JJs and demonstrate non-Abelian statistics with phase or mini-gate control, detected by charge sensing using quantum point contacts. Our proposals, supported by the experiments, would constitute an important milestone towards topological quantum computing.
11805-20
Author(s): Chien-Te Wu, Shao-Hung Huang, National Yang Ming Chiao Tung Univ. (Taiwan)
On demand starting 1 August 2021
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In this work, we focus on the emergence of Majorana zero modes in heterostructures composed of superconducting and ferromagnetic materials. We numerically determine self-consistent solutions to the Bogoliubov-de Gennes equations suitable for our system. For the first part, we consider a conventional superconductor sandwiched by two conical ferromagnets. We vary the direction of the conical axes and the strength of Zeeman field for both ferromagnetic regions to study the stability of the topological properties of our system. For the second part, we turn our attention to a trilayer consisting of two superconductors and a conical ferromagnet in the geometry of a conventional Josephson junction. By choosing appropriate parameters, the Josephson junction can also host Majorana zero modes and exhibit topological signatures.
11805-21
Author(s): Barış Pekerten, Joseph D. Pakizer, Benjamin S. Hawn, Alex Matos-Abiague, Wayne State Univ. (United States)
On demand starting 1 August 2021
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We theoretically investigate the emergence of topological superconductivity in dc-SQUIDs in the presence of Rashba spin-orbit coupling and an in-plane magnetic field. The transmission of the individual planar Josephson junctions (JJs) can be controlled by top gates, switching from a single JJ to a dc-SQUID behavior. The transition to the topological phase in the single JJ configuration is sensible to the direction of the in-plane magnetic field and we show that it is accompanied by minima in the critical current, serving as experimental signatures to identify the phase transition. Furthermore, the topological phase transitions in each of the JJs can be individually tuned by top gates. We show that there are distinctive signatures in the critical current and phase shift of the dc-SQUID for cases when none, either or both junctions are in the topological regime. We also investigate the effects of electrostatic disorder on the topological superconducting state of single JJs.
Session 6: Magnetic Inertia and Nutation
11805-22
Author(s): Imam Makhfudz, Institut Matériaux Microélectronique Nanosciences de Provence (France); Enrick Olive, GREMAN, Tours (France); Stam Nicolis, Institut Denis Poisson, université de Tours (France)
On demand starting 1 August 2021
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At short time scales, the inertia term becomes relevant for the magnetization dynamics of ferromagnets and leads to nutation for the magnetization vector. For the case of spatially extended magnetic systems, for instance, Heisenberg spin chains with the isotropic spin-exchange interaction, this leads to the appearance of a collective excitation, the “nutation wave,” whose properties are elucidated by analytical arguments and numerical studies. The one-particle excitations can be identified as relativistic massive particles. These particles, the “nutatons,” acquire their mass via the Brout–Englert–Higgs mechanism, through the interaction of the wave with an emergent topological gauge field. This spin excitation would appear as a peak in the spectrum of the scattering structure factor in inelastic neutron scattering experiments. The high frequency and speed of the nutation wave can open paths for realizing ultrafast spin dynamics.
11805-23
Author(s): Alexey M. Lomonosov, A. M. Prokhorov General Physics Institute of the RAS (Russian Federation); Vasily V. Temnov, Institut des Molécules et Matériaux du Mans (France), Ecole Polytechnique (France), CNRS (France); Jean-Eric Wegrowe, Ecole Polytechnique (France), CNRS (France), Institut Polytechnique de Paris (France)
On demand starting 1 August 2021
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We analyze dispersion relations of magnons in ferromagnetic thin films taking into account inertial terms or magnetic nutation. Inertial effects are parametrized by the damping-independent parameter $\beta$, which allows for their unambiguous discrimintation from dissipation effects characterized by the Gilbert damping parameter $\alpha$. The analysis of two distinct magnon branches shows that they are both modified by the nutation parameter $\beta$, albeit in different ways. Whereas the upper nutation branch starts at $1/\beta$, the lower branch departs from the zero-inertia parabolic dependence $\propto Dk^2$ of conventional exchange magnons. A realistic experimental geometry of a ferromagnetic thin film is used to discuss the possibility of the magneto-elastic excitation of inertial magnons by longitudinal acoustuc phonons propagating across the film. The criterium of a phase-matched excitation is found to depend on $\beta$, the exchange stiffness $D$ and the acoustic velocity.
11805-24
Author(s): Sergei V. Titov, Kotelnikov Institute of Radio Engineering and Electronics of RAS (Russian Federation); William Coffey, William J. Dowling, Trinity College Dublin (Ireland); Yuri Kalmykov, Univ. de Perpignan Via Domitia (France); Marios Zarifakis, Trinity College Dublin (Ireland), Electricity Supply Board (Ireland); Anton Titov, Moscow Institute of Physics and Technology (Russian Federation)
On demand starting 1 August 2021
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The appropriate magnetic Langevin equation is written starting from an analogy with the dynamics of the magnetic dipole moment of a current-carrying loop viewed as a symmetric top. Hence the corresponding Fokker-Planck equation for the evolution of the probability density function in the phase space of angular velocities and orientations and its stationary solution are derived. The inertial stochastic magnetization dynamics of ferromagnetic nanoparticles is also seen to be analogous to the stochastic dynamics of the electric dipole moment of a polar molecule visualized as a symmetric top ignoring friction about that axis – a conclusion reached by replacing electrical parameters with their magnetic analogs in the respective Langevin equations. Therefore, existing results from gyroscopic theory, as applied to dielectric relaxation of polar molecules, may with appropriate modifications be used to study inertial magnetization effects in ferromagnetic nanoparticles.
11805-25
Author(s): Kumar Neeraj, Stockholm Univ. (Sweden); Nilesh Awari, Sergey Kovalev, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Debanjan Polley, Nanna Zhou Hagström, Stockholm Univ. (Sweden); Sri Sai Phani Kanth Arekapudi, Technische Univ. Chemnitz (Germany); Anna Semisalova, Univ. Duisburg-Essen (Germany), Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Kilian Lenz, Bertram Green, Jan-Christoph Deinert, Igor Ilyakov, Min Chen, Mohammed Bawatna, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Valentino Scalera, Univ. degli Studi di Napoli Federico II (Italy); Massimilano d’Aquino, Univ. degli Studi di Napoli Parthenope (Italy); Claudio Serpico, Univ. degli Studi di Napoli Federico II (Italy); Olav Hellwig, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany), Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Jean-Eric Wegrowe, Ecole Polytechnique (France), CEA (France), CNRS (France); Michael Gensch, Deutsches Zentrum für Luft- und Raumfahrt e.V. (Germany), Technische Univ. Berlin (Germany); Stefano Bonetti, Stockholm Univ. (Sweden), Univ. Ca' Foscari di Venezia (Italy)
On demand starting 1 August 2021
Session 7: Ultra-Fast and THz Spintronics
11805-26
Author(s): Hans Christian Schneider, Technische Univ. Kaiserslautern (Germany)
On demand starting 1 August 2021
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Ultrashort optical pulses applied to ferromagnets excite spin polarized hot electrons. Such an ultrashort-pulse excitation is followed by spin-flip scattering due to spin-orbit coupling, "intrinsic" magnetization dynamics and spin-polarized transport. I will present some of our work concerning the interplay of spin-flip scattering due to spin-orbit coupling and exchange scattering in a model system containing itinerant electrons which are exchange-coupled to localized electronic bands. I will also present results on spin-dependent transport of optically excited hot electrons in ferromagnet-metal heterostructures which have gained interest as THz emitters in recent years.
11805-27
Author(s): Vivek Unikandanunni, Stockholm Univ. (Sweden); Rajasekhar Medapalli, National Institute of Technology, Arunachal Pradesh (India); Eric E. Fullerton, Univ. of California, San Diego (United States); Karel Carva, Charles Univ. (Czech Republic); Peter M. Oppeneer, Uppsala Univ. (Sweden); Stefano Bonetti, Stockholm Univ. (Sweden)
On demand starting 1 August 2021
11805-28
Author(s): Tom Sebastian Seifert, Freie Univ. Berlin (Germany)
On demand starting 1 August 2021
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Terahertz (THz) time-domain spectroscopy is an emerging technique to probe and manipulate spins on ultrafast time scales. In this talk, I will highlight recent results of studying spintronic phenomena at terahertz rates, which holds great promise for next-generation THz photonic applications such as broadband THz generation and detection.
11805-29
Author(s): Jacques Hawecker, Lab. de Physique de l'Ecole Normale Supérieure (France); Enzo Rongione, Laëtitia Baringthon, Unité Mixte de Physique CNRS/Thales (France); Thi-Huong Dang, Unité Mixte de Physique CNRS/Thales (France), Univ. Paris-Sud (France), Univ. Paris-Saclay (France); Giovanni G. Baez Flores, Univ. of Nebraska-Lincoln (United States); Duy-Quang TO, Juan-Carlos Rojas-Sánchez, Unité Mixte de Physique CNRS/Thales (France); Nong Hanond, Juliette Mangeney, Jerome Tignon, Lab. de Physique de l'Ecole Normale Supérieure (France); Florian Godel, Unité Mixte de Physique CNRS/Thales (France); Sophie Collin, Unité Mixte de Physique CNRS/Thales (France), Univ. Paris-Sud (France), Univ. Paris-Saclay (France); Pierre Seneor, Nicolas Reyren, Manuel Bibes, Albert Fert, Unité Mixte de Physique CNRS/Thales (France); Abdelmadjid Anane, Unité Mixte de Physique CNRS/Thales (France); Jean-Marie George, Unité Mixte de Physique CNRS/Thales (France); Laurent Vila, Univ. Grenoble Alpes (France), CEA (France), CNRS (France); Cosset-Cheneau Maxen, Univ. Grenoble Alpes (France); Vincent Cros, Agnès Barthélemy, Unité Mixte de Physique CNRS/Thales (France); Daniel Dolfi, Thales Research & Technology (France); Romain Lebrun, Paolo Bortolotti, Unité Mixte de Physique CNRS/Thales (France); Kirill D. Belashchenko, Univ. of Nebraska-Lincoln (United States); Sukhdeep S. Dhillon, Lab. de Physique de l'Ecole Normale Supérieure (France); Henri Jaffrès, Unité Mixte de Physique CNRS/Thales (France); Luca Perfetti, Laboratoire des Solides Irradiés CEA/DRF/lRAMIS, Ecole Polytechnique, CNRS (France); Henri-Jean Drouhin, Yannis Laplace, Romain Grasset, Jingwei Dong, Laboratoire des Solides Irradiés CEA/DRF/lRAMIS (France); Gilles Patriarche, Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Sud, Université Paris-Saclay (France); Patrick Le Fèvre, Synchrotron SOLEIL (France); Aristide Lemaître, Centre for Nanoscience and Nanotechnology (France); Athanasios Dimoulas, National Center for Scientific Research Demokritos (Greece); Claudia Felser, Max Planck Institute for Chemical Physics of Solids (Germany)
On demand starting 1 August 2021
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THz emission spectroscopy reveals to be a very powerful experimental method to investigate the properties of Rashba or topological insulator surface states. The THz emission can be also used in heavy metallic or in more general Rashba systems. We prove here the ability of the present method. In 3d/5d transient metal bilayers and beyond heavy metal structures, Rashba states and Topological insulators are expected candidates for spintronic-terahertz domains due to their high spin to charge conversion properties. In this scheme, we are interested in the samples based on 2D electron gas, topological insulators and Heusler alloys with strong spin-orbit coupling.
Session 8: Ultra-Fast Spintronics and Magnetoplasmonics
11805-30
Picosecond spintronics (Invited Paper)
Author(s): Jon Gorchon, CNRS (France)
On demand starting 1 August 2021
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Reducing energy dissipation while increasing speed in computation and memory is a long-standing challenge for spintronics research. In the last 20 years, femtosecond lasers have emerged as a tool to control the magnetization in specific magnetic materials at the picosecond timescale. However, the use of ultra-fast optics in integrated circuits and memories would require a major paradigm shift. An ultrafast electrical control of the magnetization is far preferable for integrated systems. In a recent work, we demonstrate reliable and deterministic control of the out-of-plane magnetization of a 1 nm-thick Co layer with single 6 ps-wide electrical pulses that induce spin orbit torques on the magnetization. These experiments show that spintronic phenomena can be exploited on picosecond time-scales for full magnetic control and should launch a new regime of ultrafast spin torque studies and applications.
11805-31
Author(s): Ilie E. Radu, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (Germany)
On demand starting 1 August 2021
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We report on the first demonstration of THz-driven ultrafast magnetization switching of a magnetically ordered material using intense, single-cycle THz pulses. The magnetization switching process evolves on a sub-picosecond timescales as probed by time-resolved magneto-optics in visible and XUV spectral range. Our findings reveal a fully deterministic switching event occurring upon each single-shot THz excitation of the ferrimagnetic GdFe alloy in the absence of a symmetry-breaking magnetic field.
11805-32
Author(s): Nicolas Tiercelin, Geoffrey Lezier, Institut d'Electronique de Microélectronique et de Nanotechnologie (France); Pierre Koleják, VŠB-Technical Univ. of Ostrava (Czech Republic); Jean-François Lampin, Institut d'Electronique de Microélectronique et de Nanotechnologie (France); Kamil Postava, VŠB-Technical Univ. of Ostrava (Czech Republic); Mathias Vanwolleghem, Institut d'Electronique de Microélectronique et de Nanotechnologie (France)
On demand starting 1 August 2021
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We present a scheme to achieve coherent polarization rotation without multipolar or rotating external magnetic bias nor complex cascaded emitters, by exploiting artificially engineered strong uniaxial anisotropy in intermetallic heterostructures of rare-earth and transition metals. By replacing the FM layer of the spintronic emitter with a carefully designed FeCo/TbCo2/FeCo heterostructure, we demonstrated Stoner-Wolfarth-like coherent rotation of the THz polarization only by a unipolar variation of the strength of the hard axis field. In a second step we demonstrated the magnetoelectric control of the polarization direction. These results improve greatly the feasibility of fast polarization switchable integrated THz sources impacting practical applications such as ultrabroadband THz spectroscopic ellipsometry without rotating elements, or polarization modulated high speed wireless data communications, but also fundamental physical studies into ultrafast terahertz optospintronics.
11805-33
Author(s): Dmitry A. Kuzmin, Igor V. Bychkov, Chelyabinsk State Univ. (Russian Federation); Vladimir G. Shavrov, Kotelnikov Institute of Radio Engineering and Electronics of RAS (Russian Federation); Vasily V. Temnov, Institut des Molécules et Matériaux du Mans (France)
On demand starting 1 August 2021
Session 9: Antiferromagnetic Spintronics
In person: 1 August 2021 • 2:00 PM - 2:30 PM PDT | Conv. Ctr. Room 2
11805-35
Author(s): Pedram Khalili, Northwestern Univ. (United States)
In person: 1 August 2021 • 2:00 PM - 2:30 PM PDT | Conv. Ctr. Room 2
11805-34
Author(s): Mathias Klaeui, Johannes Gutenberg Univ. Mainz (Germany)
On demand starting 1 August 2021
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While known for a long time, antiferromagnetically ordered systems have previously been considered, as expressed by Louis Néel in his Nobel Prize Lecture, to be “interesting but useless”. However, since antiferromagnets potentially promises faster operation, enhanced stability with respect to interfering magnetic fields and higher integration due to the absence of dipolar coupling, they could potentially become a game changer for new spintronic devices. The zero net moment makes manipulation using conventional magnetic fields challenging. However recently, these materials have received renewed attention due to possible manipulation based on new approaches such as photons or spin-orbit torques. In this talk, we will present an overview of the key features of antiferromagnets to potentially functionalize their unique properties. This includes writing, reading and transporting information using antiferromagnets. This talk is supported as an IEEE Magnetics Society Distinguished Lecturer.
11805-36
Author(s): Shutaro Karube, Daichi Sugawara, Naohiro Kadoguchi, Makoto Kohda, Junsaku Nitta, Tohoku Univ. (Japan)
On demand starting 1 August 2021
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Ruthenium oxide (RuO2) has several intriguing properties such as electrically-conduction like metal, topological electronic band structure called Dirac nodal line, and room temperature collinear antiferromagnet (AFM) [T. Berlijn et al, Phys. Rev. Lett. 118, 077201 (2017)]. We have discovered a novel spin-orbit torque (SOT) generation in epitaxially grown RuO2 thin films originated from recently predicted magnetic spin Hall effect (MSHE) [R. Gonzalez-Hernandez et al, arXiv:2002.07073(2020)]. The detected both damping-like and field-like torques clearly follow the Néel vector directions against the applied current directions in the epitaxial RuO2(101) and RuO2(100) films which have different Néel vectors on the substrate plane. We further discuss the mechanism of the SOT and the related phenomena in the AFM RuO2 films on this conference.
11805-37
Author(s): Hendrik Meer, Felix Schreiber, Christin Schmitt, Johannes Gutenberg Univ. Mainz (Germany); Rafael Ramos, CIQUIS, Univ. de Santiago de Compostela (Spain), Advanced Institute for Materials Research, Tohoku Univ. (Japan); Eiji Saitoh, Advanced Institute for Materials Research, Tohoku Univ. (Japan), The Univ. of Tokyo (Japan); Olena Gomonay, Jairo Sinova, Lorenzo Baldrati, Mathias Kläui, Johannes Gutenberg Univ. Mainz (Germany)
On demand starting 1 August 2021
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We unambiguously identify the origin of the current-induced magnetic switching of insulating antiferromagnet/heavy metal bilayers. Previously, different reorientations of the Néel order for the same current direction were reported for different device geometries and different switching mechanisms were proposed. Here, we combine concurrent electrical readout and optical imaging of the switching of antiferromagnetic domains with simulations of the current-induced temperature and strain gradients. By comparing the switching in specially engineered NiO/Pt device and pulsing geometries, we can rule out spin-orbit torque based mechanisms and identify a thermomagnetoelastic mechanism to dominate the switching of antiferromagnetic domains, reconciling previous reports.
11805-102
Author(s): Hai Zhong, Qnami AG (Switzerland); Johanna Fischer, Unité Mixte de Physique, CNRS, Thales, Université Paris Saclay (France); Angela Haykal, Aurore Finco, Laboratoire Charles Coulomb, CNRS, Université de Montpellier (France); Alexander Stark, Felipe Favaro de Oliveira, Patrick Maletinsky, Mathieu Munsch, Qnami AG (Switzerland); Karim Bouzehouane, Stéphane Fusil, Unité Mixte de Physique, CNRS, Thales, Université Paris Saclay (France); Vincent Jacques, Laboratoire Charles Coulomb, CNRS, Université de Montpellier (France); Vincent Garcia, Unité Mixte de Physique, CNRS, Thales, Université Paris Saclay (France)
On demand starting 1 August 2021
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Antiferromagnetic thin films attract significant interest for future low-power spintronic devices [1]. Multiferroics, such as bismuth ferrite BiFeO3, in which antiferromagnetism and ferroelectricity coexist at room temperature, appears as a unique platform for spintronic [2] and magnonic devices [3]. The nanoscale structure of its ferroelectric domains has been widely investigated with piezoresponse force microscopy (PFM), revealing unique domain structures and domain wall functionalities [4]. However, the nanoscale magnetic textures present in BiFeO3 and their potential for spin-based technology remain concealed. In this report, we present two different antiferromagnetic spin textures in multiferroic BiFeO3 thin films with different epitaxial strains, using a commercial non-invasive scanning Nitrogen-Vacancy (NV) magnetometer based on a single NV defect in diamond, with a calibrated NV flying height of 60 nm and a proven DC field sensitivity of 1 T/Hz. Two BiFeO3 samples were grown on DyScO3 (110) and SmScO3 (110) substrates (later mentioned as BFO/DSO and BFO/SSO, respectively) using pulsed laser deposition. The striped ferroelectric domains in both samples are first observed by the in-plane PFM. The scanning NV magnetometry (SNVM) confirms the existence of the spin cycloid texture, with zig-zag wiggling angles of 90 and 127, and propagation wavelength of DSO=64 nm andSSO=103 nm, respectively. At the local scale, the combination of PFM and SNVM allows to identify the relative orientation of the ferroelectric polarization and cycloid propagation directions on both sides of a domain wall. For the BFO/DSO sample, the 90-degree in-plane rotation of the ferroelectric polarization imprints the 90-degree in-plane rotation of the cycloidal propagation direction along k1=[-1 1 0], corresponding to the type-I cycloid. On the contrary, in the BFO/SSO sample, the propagation vectors are found to be along k1'=[-2 1 1] and k2'= [1 -2 1] directions in the neighboring domains separated by the 71 domain wall. It is worth to mentioned that in the previous report [5], BFO/SSO, prepared in another growth chamber, showed G-type antiferromagnetic textures, compared to the observed type-II cycloid here. Our results here shed the light on future potential for reconfigurable nanoscale spin textures on multiferroic systems by strain engineering.
Session 10: Spin Lasers I
11805-40
Author(s): Mariusz Drong, VŠB-Technical Univ. of Ostrava (Czech Republic); Henri Jaffrès, Unité Mixte de Physique CNRS/Thales (France); Jan Peřina, The Joint Laboratory of Optics (Czech Republic); Tibor Fördös, Kamil Postava, VŠB-Technical Univ. of Ostrava (Czech Republic); Henri-Jean M. Drouhin, Ecole Polytechnique (France)
On demand starting 1 August 2021
11805-38
Author(s): Natalie Jung, Markus Lindemann, Ruhr-Univ. Bochum (Germany); Tobias Pusch, Rainer Michalzik, Univ. Ulm (Germany); Martin R. Hofmann, Nils C. Gerhardt, Ruhr-Univ. Bochum (Germany)
On demand starting 1 August 2021
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Spin-polarized vertical-cavity surface-emitting lasers (spin-VCSELs) have proven to be a highly promising device technology for high-speed optical communication systems. In spin-lasers, the polarization state of the laser emission can be controlled by the carrier spin state exploiting the transfer of angular momentum between carriers and photons. The resonance frequency of the polarization dynamics can be increased by inducing birefringence into the resonator. Spin-VCSELs with polarization dynamics above 200 GHz have been demonstrated already, which potentially provide data transmission rates of more than 240 Gbits/s. Here we present our recent results on how to control and integrate birefringence and how this can be combined with electrical spin injection. We discuss the role of important device parameters and show results on the influence of these parameters on the polarization dynamics.
11805-39
Author(s): Nikolay Ledentsov, Lukasz Chorchos, VI Systems GmbH (Germany), Warsaw Univ. of Technology (Poland); Oleg Y. Makarov, Marwan Bou Sanayeh, Joerg-Reinhardt Kropp, Vitaly A. Shchukin, Vladimir P. Kalosha, VI Systems GmbH (Germany); Jaroslaw P. Turkiewicz, Warsaw Univ. of Technology (Poland); Nikolay N. Ledentsov, VI Systems GmbH (Germany)
On demand starting 1 August 2021
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Strain-induced birefringence in GaAs-based oxide-confined VCSELs (Vertical-Cavity Surface-Emitting Laser) can split the optical modes into orthogonally polarized components. A polarization switching at very high frequencies occurs between these components that is of great interest for the optical communication systems of the future. We focus this investigation on the frequency characteristics of the polarization switching between the optical modes caused by polarization self‐modulation (PSM) in fiber-coupled systems. We analyze the stability of the PSM in view of the temperature, driving current and optical coupling and compare various multi-mode and single-mode VCSELs.
Session 12: Magnetism and Chirality I
In person: 1 August 2021 • 2:30 PM - 3:00 PM PDT | Conv. Ctr. Room 2
11805-45
Author(s): Robert Streubel, Univ. of Nebraska-Lincoln (United States)
In person: 1 August 2021 • 2:30 PM - 3:00 PM PDT | Conv. Ctr. Room 2
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To date, the emergence of topological vector fields has almost exclusively been associated with a global inversion symmetry breaking that causes a vector spin exchange, known as Dzyaloshinskii-Moriya interaction. Engineering a locally varying vector spin exchange has been proposed as an alternative to stabilize anisotropic topological states. I will present experimental evidence of 3D chiral spin textures stabilized in amorphous iron germanium thick films with local inversion symmetry breaking and DMI [1]. Lorentz microscopy with exit wave reconstruction revealed both isotropic Bloch skyrmions and anisotropic solitons, which are accompanied by a reduced orbital-to-spin moment ratio, underling the importance of disordered electron orbitals and random DMI. Persistent switching of anisotropic skyrmions corroborate variations in magnetic anisotropy and exchange, and confirm a degenerate spin chirality and particle-like properties. [1] RS et al., Adv. Mater. DOI: 10.1002/adma.202004830
11805-46
Author(s): Maria Lifshits, Konstantin Denisov, Igor Rozhansky, Ioffe Institute (Russian Federation)
On demand starting 1 August 2021
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We consider a new mechanism for the spin current swapping effect. The effect manifests in the appearance of the transverse spin current qyx of the spin projection along x in the direction of y, in response to the longitudinal spin current of spin projection along y flowing in x direction with swapped indices qxy, hence the name spin swapping. We show that in the presence of a chiral spin texture primary spin current produces the transverse spin current. This spin-related transport phenomenon is similar to that known for electron scattering on a charged impurity with the account of correlation between the spin rotation and the scattering angle due to spin-orbit interaction. The discussed spin swapping mechanism originates from the electron spin correlations in real space due to an exchange interaction with chiral spin textures such as magnetic skyrmions. The spin swapping effect exists already in the first Born approximation.
11805-47
Author(s): Wei Chen, Matheus de Sousa, Pontifical Catholic Univ. of Rio de Janeiro (Brazil); Manfred Sigrist, ETH Zurich (Switzerland)
On demand starting 1 August 2021
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We elaborate that Rashba spin-orbit coupling causes an out-of-plane polarized helical edge spin current at the boundaries of 2D metals. In the presence of a magnetization pointing perpendicular to the edge, an edge charge current is also produced, which can be either chiral or nonchiral depending on whether the magnetization lies in-plane or out-of-plane. The spin polarization near the edge develops a transverse component orthogonal to the magnetization, which tends to cause a noncollinear magnetic order between the two edges. If the magnetization only occupies a region near one edge, or in an irregular shaped quantum dot, this transverse component renders a gate voltage-induced magnetoelectric torque without the need of a bias voltage. We also argue that these phenomena are generic effects of a variety of spin-orbit couplings irrespective of the detail of the band structure, as also demonstrated for the Dresselhaus spin-orbit coupling and graphene nanoribbons.
Break
Coffee Break 3:00 PM - 3:40 PM
Session 11: Spin Lasers II
11805-41
Author(s): Aniruddha Bhattacharya, Univ. of Washington (United States)
On demand starting 1 August 2021
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A spin polariton diode laser is a solid-state quantum optoelectronic device, which offers intrinsic control of the nature of the output circular polarization. In the present work, we have demonstrated electrical spin injection from a FeCo/MgO tunnel barrier contact in an electrically pumped spin polariton diode laser. The polariton lasing characteristics have been measured with spin-polarized injection current in remanence after magnetization of the contacts with H ∼ 1.6 kOe. Above the polariton lasing threshold, a maximum value of the steady-state output circular (linear) polarization of ∼ 25 (33)% is observed. The measured output circular and linear polarization have been analyzed by solving the rate equations for free carriers and excitons and the Gross-Pitaevskii equations for the polariton condensate. The device represents a room-temperature bias-tunable low-energy semiconductor source of coherent circularly polarized UV light.
11805-42
Author(s): Nobuhide Yokota, Tohoku Univ. (Japan); Kazuhiro Ikeda, National Institute of Advanced Industrial Science and Technology (Japan); Hiroshi Yasaka, Tohoku Univ. (Japan)
On demand starting 1 August 2021
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We investigate the use of spin-VCSELs for transmitters in analog radio-over-fiber systems by using a spin-flip rate equation model. In addition to the current modulation for generating data signals, we use the spin polarization modulation to excite a high-frequency polarization oscillation corresponding to a millimeter-wave carrier frequency. The polarization oscillation is converted to intensity modulation by using a polarizer and millimeter-wave carrier with data signals can be generated. Additionally, we report on a preliminary experiment without the spin polarization modulation to confirm that orthogonally polarized two tones of a birefringent VCSEL can be used for generating a high-frequency carrier component.
11805-43
Author(s): Tobias Heuser, Niels Heermeier, Jan Große, Technische Univ. Berlin (Germany); Natalie Jung, Markus Lindemann, Nils C. Gerhardt, Martin R. Hofmann, Ruhr-Univ. Bochum (Germany); Stephan Reitzenstein, Technische Univ. Berlin (Germany)
On demand starting 1 August 2021
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Spin-controlled lasers are highly interesting photonic devices and have been shown to provide ultra-fast polarization dynamics in excess of 200 GHz. Another class of modern semiconductor lasers are high-beta emitters which benefit from enhanced light-matter interaction due to strong mode confinement in low-mode-volume microcavities. We combine the advantages of both laser types to demonstrate spin-lasing in high-beta microlasers for the first time. For this purpose, we realize bimodal high-beta quantum dot micropillar lasers for which the mode splitting and the polarization-oszillation frequency can be engineered via the pillar cross-section. The microlasers show very pronounced spin-lasing effects with polarization oscillation frequencies up to 16 GHz.
Session 13: Magnetism and Chirality II
11805-48
Author(s): Igor Rozhansky, Konstantin Denisov, Mikhail Rakitskii, Nikita Averkiev, Ioffe Institute (Russian Federation); Henri Jaffres, Unit ́e Mixte de Physique, CNRS, Thales, Univ. Paris-Sud,Universit ́e Paris-Saclay (France); Henri-Jean Drouhin, Ecole Polytechnique, CEA/DRF/IRAMIS, CNRS,Institut Polytechnique de Paris (France)
On demand starting 1 August 2021
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We consider a transverse electrical and spin current response to a longitudinal electric field in a metallic or semiconductor system characterized by various types of chirality. Using the similar theoretical approach we study a skew scattering on magnetic skyrmions leading to topological Hall effect, tunneling anomalous Hall effect (TAHE) of electrons and holes across an interface between magnetic semiconductors and electron scattering on a magnetic center in a semiconductor. We demonstrate how the chiral symmetry of the system manifests itself in the Hall response and its dependence on the electron spin polarization.
11805-49
Author(s): Yuli Lyanda-Geller, Purdue Univ. (United States); Vadim Ponomarenko, Ioffe Institute (Russian Federation); Ying Wang, Leonid Rokhinson, Purdue Univ. (United States)
On demand starting 1 August 2021
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Parafermions or Fibonacci anyons leading to universal quantum computing, require strongly interacting systems. A leading contender is the fractional quantum Hall effect, FQHE, where helical channels can arise from counter-propagating chiral modes. These modes have been considered weakly interacting. However experiments on transport in helical channels in the fractional quantum Hall effect at a 2/3 filling shows resistance ninefold smaller than expected. We develop a microscopic theory of strongly interacting helical states and show that emerging helical Luttinger liquid manifests itself as unequally populated charge, spin and neutral modes in polarized and unpolarized FQHE liquids. We show that at strong coupling counter-propagating modes of opposite spin polarization emerge at the sample edges, providing a viable path for generating proximity topological superconductivity and parafermions. Current, calculated in stongly interacting picture is in agreement with the experiments data.
11805-50
Author(s): Kevin Hofhuis, Aleš Hrabec, Hanu Arava, Paul Scherrer Institut (Switzerland); Naëmi Leo, CIC nanoGUNE (Spain); Yen-Lin Huang, Berkeley (United States); Rajesh Chopdekar, Lawrence Berkeley National Laboratory (United States); Sergii Parchenko, Armin Kleibert, Paul Scherrer Institut (Switzerland); Sabri Koraltan, Claas Abert, Christoph Vogler, Dieter Suess, University of Vienna (Austria); Peter M. Derlet, Laura J. Heyderman, Paul Scherrer Institut (Switzerland)
On demand starting 1 August 2021
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The lowest achievable blocking temperature limits magnetic ordering in highly frustrated thermally active artificial kagome spin ice. By exploiting the interfacial Dzyaloshinskii-Moriya interaction, we can lower the blocking temperature of individual nanomagnets without strongly affecting their magnetic moments, thus leaving the critical transition temperatures unchanged. Using this approach, we demonstrate that a seven-ring kagome structure consisting of 30 nanomagnets can be thermally annealed into its ground state. Furthermore, the spin-ice correlations extracted from extended kagome lattices are found to exhibit the quantitative signatures of long-range charge-order, thereby giving experimental evidence for the theoretically predicted continuous transition to a charge-ordered state.
Session 14: Spin Logic and Devices
In person: 1 August 2021 • 3:40 PM - 4:40 PM PDT | Conv. Ctr. Room 2
11805-52
Author(s): Alexander Khitun, Univ. of California, Riverside (United States)
In person: 1 August 2021 • 3:40 PM - 4:10 PM PDT | Conv. Ctr. Room 2
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We provide a comprehensive progress update on spin wave logic circuits. First, we will present experimental data on magnetic bit readout using spin waves. The data are collected for Y3Fe2(FeO4)3 waveguide matrix with cobalt magnets placed on top of the waveguides. The magnetization direction of the magnets is recognized by the level of the inductive voltage produced by the spin waves. This approach allows us to retrieve information from a number of bits in parallel. Second, we will present experimental data on magnetic database search using spin wave superposition. The data are collected for the multi-port YIG devices. The applying of wave superposition makes it possible to speed up the search procedure compared to conventional magnetic memory. Finally, we will present experimental data on prime factorization using spin wave multi-port interferometers. The shortcomings and physical limits of spin wave logic devices will be also discussed.
11805-96
Author(s): Nicholas Smith, Brenden A. Magill, Rathsara R. H. H. Mudiyanselage, Virginia Polytechnic Institute and State Univ. (United States); Hiro Munekata, Tokyo Institute of Technology (Japan); Giti A. Khodaparast, Virginia Polytechnic Institute and State Univ. (United States)
In person: 1 August 2021 • 4:10 PM - 4:40 PM PDT | Conv. Ctr. Room 2
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Co/Pd thin film multilayers show large Perpendicular Magnetic Anisotropy (PMA) which is useful in MRAM devices for perpendicular magnetic recording. Co/Pd systems have been studied extensively through the use of ultrafast optical pump-probe methods in order to measure the Time Resolved Photo-excited Precession of Magnetization (TRPEPM). Most studies have been conducted at high laser fluence (> 1 mJ/cm2), where heating near the curie temperature occurs. In this study, we present low fluence measurements between 0.42 to 3.14 µJ/cm2 in Co/Pd systems with differing Co thickness between 0.4 to 0.74 nm to probe the role of interface anisotropy in low-power excitation.
11805-53
Author(s): Johannes Ender, Roberto Orio, Simone Fiorentini, Siegfried Selberherr, Technische Univ. Wien (Austria); Wolfgang Goes, SILVACO Europe Ltd. (Austria); Viktor Sverdlov, Technische Univ. Wien (Austria)
On demand starting 1 August 2021
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We employ a reinforcement learning strategy for finding switching schemes for deterministic switching of a spin-orbit torque magnetoresistive random access memory (SOT-MRAM) cell. The free layer of the memory cell is perpendicularly magnetized, and the spin-orbit torques are generated by currents through two orthogonal heavy metal wires. A rewarding scheme for the reinforcement learning approach is defined such that the objective of the algorithm is to find a pulse sequence which leads to fast switching of the memory cell. The reliability of the found switching scheme is confirmed by micromagnetic simulations based on the finite difference method.
11805-105
Author(s): Ke Wang, Univ. of Minnesota, Twin Cities (United States)
On demand starting 1 August 2021
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The relativistic charge carriers in monolayer graphene can be manipulated in manners akin to conventional optics (electron-optics): angle-dependent Klein tunneling collimates an electron beam (analogous to a laser), while a Veselago refraction process focuses it (analogous to an optical lens). Both processes have been previously investigated, but the collimation and focusing efficiency have been reported to be relatively low even in state-of-the-art ballistic pn-junction devices. In this talk, we will present a novel device architecture of a graphene microcavity defined by carefully-engineered local strain and electrostatic fields. We create a controlled electron-optic interference process at zero magnetic field as a consequence of consecutive Veselago refractions in the microcavity, which we utilize to localize uncollimated electrons and further improve collimation efficiency.
Nanoscience + Engineering Plenary Session
In person: 2 August 2021 • 8:25 AM - 11:20 AM PDT | Conv. Ctr. Room 6A
11797-501
Mark Stockman Tribute (Plenary Presentation)
In person: 2 August 2021 • 8:25 AM - 8:50 AM PDT | Conv. Ctr. Room 6A
11803-501
Author(s): P. James Schuck, Columbia Univ. (United States)
In person: 2 August 2021 • 8:50 AM - 9:30 AM PDT | Conv. Ctr. Room 6A
Coffee Break 9:30 AM - 10:00 AM
11797-502
Author(s): Teri W. Odom, Northwestern Univ. (United States)
In person: 2 August 2021 • 10:00 AM - 10:40 AM PDT | Conv. Ctr. Room 6A
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This talk will discuss current advances and future prospects in manipulating light at the nanoscale by plasmonic nanoparticle lattices. These meta-materials support collective hybrid resonances with both light scattering and localization properties. First, we will describe the expanded scope of plasmonic lattices based on exquisite tuning of topological symmetries and nanoparticle materials. Next, we will highlight how the nanoscale cavities combined with quantum emitters show unprecedented nano-lasing properties. Finally, we will discuss how this platform is opening new opportunities in imaging, strong coupling, and photoelectrocatalysis.
11795-501
Author(s): David R. Smith, Duke Univ. (United States)
In person: 2 August 2021 • 10:40 AM - 11:20 AM PDT | Conv. Ctr. Room 6A
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In recent years, metamaterials have successfully transitioned from fascinating lab demonstrations to fully functional commercial products. The innovations that have driven this success are tied to underlying metamaterial properties that provide key benefits for system architectures. Metamaterial design is inspired by insights from material science and thus deviates from traditional engineering paths, providing new opportunities. Yet, the metamaterial component is just one part of the system, and must interact appropriately with the electronics, processing and other requisite subsystems. In this talk, I will describe how the challenges of system design with metamaterial components have been met, providing several examples.
Nanoscience + Engineering Plenary Networking Event
In person: 2 August 2021 • 11:20 AM - 11:50 AM PDT | Conv. Ctr. Room 6A
Join your colleagues for 30 minutes of networking and discussion after the Nanoscience + Engineering plenary talks.
Break
Lunch 11:50 AM - 1:30 PM
Session 15: Spin Sensors
11805-54
Author(s): Denys Makarov, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany)
On demand starting 1 August 2021
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Conventional magnetic field sensors are fabricated on flat substrates and are rigid. Extending 2D structures into 3D space relying on the flexible electronics approaches allows to enrich conventional or to launch novel functionalities of spintronic-based devices. Here, we will review fundamentals of 3D curved magnetic thin films and primarily focus on their application potential for eMobility, virtual and augmented reality appliances. The technology platform relies on high-performance magnetoresistive and Hall effect sensors fabricated on ultrathin polymeric foils and paves the way towards skin-compliant devices enabling touchless interactivity with our surroundings. Flexile magnetosensitive elements impact emerging research and technology fields of smart skins, soft robotics and human-machine interfaces. In this talk, recent fundamental and technological advancements on flexible magnetoelectronics will be reviewed.
11805-55
Author(s): Hang Xie, Xin Chen, National Univ. of Singapore (Singapore); Ziyan Luo, National Univ. of Singapore (Singapore), Central South Univ. (China); Yihong Wu, National Univ. of Singapore (Singapore)
On demand starting 1 August 2021
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Spin-orbit torque offers an efficient route to manipulate the magnetic state of magnetic materials, which is of great importance for energy-efficient applications of various spintronic devices like memory, logic, oscillator, and neuromorphic computing. Here, we propose a strategy for the realization of a spin torque gate magnetic field sensor with an extremely simple structure by utilizing the longitudinal field dependence of the spin-orbit torque driven magnetization switching. This sensor does not require any magnetic bias to achieve a linear response to the external field, which is the main cause of high cost of all types of magnetoresistance sensors. In addition, zero offset can be achieved in the spin torque gate sensor without complicated offset compensation circuit. By employing the WTe2/Ti/CoFeB structure with both large spin-orbit torque and well-defined PMA, we demonstrate that the sensor can work linearly in the range of ±3-10 Oe with nearly zero dc offset.
11805-57
Author(s): Christian Degen, Pol Welter, ETH Zurich (Switzerland)
On demand starting 1 August 2021
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Diamond has emerged as a unique material for a variety of applications, both because it is very robust and because it has defects with interesting properties. One of these defects, the nitrogen-vacancy center (NV center), has a single spin associated with it that shows quantum behavior up to room temperature. Our group is harnessing the properties of single NV centers for high resolution magnetic sensing applications. In this talk, I will introduce the basic concepts and emerging applications of diamond-based quantum sensors. I will discuss the challenges in the fabrication of diamond probes and their integration into scanning probe microscopy (SPM) systems. I will then present some illustrative examples of applications in nanoscale magnetism, including the imaging of antiferromagnetic domains and domain walls, the flow of current in graphene devices, and magnetic resonance imaging of nuclear spins with atomic spatial resolution.
Session 16: Neuromorphic Computing
11805-59
Author(s): Thomas J. Hayward, Ian T. Vidamour, Matthew O.A. Ellis, Alexander Welbourne, Richard W.S. Dawidek, Thomas J. Broomhall, Morgan Chambard, Marie Drouhin, Alyshia M. Keogh, Aidan Mullen, Stephan J. Kyle, Mohanad Al Mamoori, Paul W. Fry, The Univ. of Sheffield (United Kingdom); Nina-Juliane Steinke, Institut Laue-Lagevin (France); Jos F. K. Cooper, ISIS Synchrotron (United Kingdom); Francesco Maccherozzi, Sarnjeet Dhesi, Diamond Light Source (United Kingdom); Lucia Aballe, Jordi Prat, ALBA Synchrotron (Spain); Eleni Vasilaki, Dan Allwood, The Univ. of Sheffield (United Kingdom)
On demand starting 1 August 2021
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Domain walls (DWs) in magnetic nanowires have been of intense interest due to proposals to use them to represent data in logic and memory devices. However, these have been challenging to realise because DWs behaviour is highly stochastic, making conventional digital devices unreliable. Here, we show how embracing DW stochasticity as a functional feature can facilitate novel computational devices. We first present results showing how integrating tuneable stochastic DW pinning into DW logic networks allows “stochastic computing”, where numbers are represented by random bit streams and individual logic gates perform complex mathematical operations. We then go on to demonstrate how DW stochasticity can be used to facilitate neuromorphic devices: (a) a neural network where the probabilities of DW propagation through nanowires perform the roles of synaptic weights and (b) a reservoir computing platform based on the emergent dynamics of DWs within an extended nanowire ensemble.
11805-60
Author(s): Jayasimha Atulasimha, Virginia Commonwealth Univ. (United States)
On demand starting 1 August 2021
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Skyrmion manipulation with VCMA can lead to small footprint nanomagnetic memory [1-2]. This talk will focus on experimental demonstration of VCMA induced nonvolatile creation and annihilation of skyrmions in an antiferromagnet/ferromagnet/oxide heterostructure film [3]. This could provide a pathway for using intermediate skyrmion states [4] to enable robust magnetization reversal with VCMA. We will discuss its scaling to lateral dimensions below 50 nm [5], oscillations > 50 GHz [5] and application to neuromorphic computing. 1. D. Bhattacharya et al, Sci. Rep., 6, 31272, 2016 2. Y. Nakatani et al, Appl. Phys. Lett., vol. 108, no. 15, 2016. 3. D. Bhattacharya et al, Nature Electronics, 3, 539, 2020. 4. D. Bhattacharya et al, ACS Appl Mat. Inter. 10 (20), pp 17455–17462, 2018. 5. M. M. Rajib et al., IEEE Transactions on Electron Devices 67 (9), 3883, 2020. Acknowledgment: NSF grants CCF-1909030, CCF-1253370, NSF ECCS-1609303. Experiments in collaboration with Prof. K.L. Wang's group.
11805-61
Author(s): Naimul Hassan, Wesley H. Brigner, The Univ. of Texas at Dallas (United States); Christopher H. Bennett, Sandia National Labs. (United States); Alvaro Velasquez, Air Force Research Lab. (United States); Xuan Hu, The Univ. of Texas at Dallas (United States); Samuel Liu, Can Cui, The Univ. of Texas at Austin (United States); Matthew J. Marinella, Sandia National Labs. (United States); Felipe Garcia-Sanchez, Univ. de Salamanca (Spain); Jean Anne C. Incorvia, The Univ. of Texas at Austin (United States); Joseph S. Friedman, The Univ. of Texas at Dallas (United States)
On demand starting 1 August 2021
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We propose a four-terminal domain wall-magnetic tunnel junction (DW-MTJ) neuron that enables the first-ever purely spintronic multilayer perceptron with unsupervised learning. The leaky integrate-and-fire neuron has a ferromagnetic DW track coupled to a binary MTJ by an electrically insulated layer. Current through the DW track performs integration by moving the DW. Leaking occurs by moving the DW in the opposite direction of integration due to either dipolar magnetic field, anisotropy gradient, or shape variation. When the DW passes underneath the MTJ, it fires by switching between the resistive and conductive states. In a crossbar perceptron, the DW track of each neuron is connected to the analog three-terminal DW-MTJ synapses and the MTJ terminals cascade multiple layers. Finally, an unsupervised learning algorithm results from the feedback between the neuron MTJ and the analog synapses, providing best results of 98.11% accuracy on the Wisconsin breast cancer clustering task.
11805-62
Author(s): Dedalo Sanz-Hernandez, Unité Mixte de Physique CNRS/Thales (France); Maryam Massouras, Institut Jean Lamour (France); Nicolas Reyren, Unité Mixte de Physique CNRS/Thales (France); Nicolas Rougemaille, Institut NÉEL (France); Vojtěch Schánilec, Institut NÉEL (France), CEITEC- Central European Institute of Technology (Czech Republic); Karim Bouzehouane, Unité Mixte de Physique CNRS/Thales (France); Michel Hehn, Institut Jean Lamour (France); Benjamin Canals, Institut NÉEL (France); Damien Querlioz, Ctr. de Nanosciences et de Nanotechnologies (France); Julie Grollier, Unité Mixte de Physique CNRS/Thales (France); François Montaigne, Institut Jean Lamour (France); Daniel Lacour, Institut NÉEL (France)
On demand starting 1 August 2021
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In this work , we describe the design, realisation and characterization of the magnetic version of the Galton Board, an archetypal statistical device originally designed to exemplify normal distributions. Although simple in its macroscopic form, achieving an equivalent nanoscale system poses many challenges related to the generation of sufficiently similar nanometric particles and the strong influence that nanoscale defects can have in the stochasticity of random processes. We demonstrate how the quasi-particle nature and the chaotic dynamics of magnetic domain-walls can be harnessed to create nanoscale stochastic devices [1]. Furthermore, we show how the direction of an externally applied magnetic field can be employed to controllably tune the probability distribution at the output of the devices, and how the removal of elements inside the array can be used to modify such distribution [1]. [1] arXiv:2010.10389 [cond-mat.mes-hall], In-press as: 10.1002/adma.202008135
Session 17: Spin Decoherence
In person: 2 August 2021 • 1:30 PM - 2:00 PM PDT | Conv. Ctr. Room 2
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Author(s): Denis R. Candido, Michael E. Flatté, The Univ. of Iowa (United States)
In person: 2 August 2021 • 1:30 PM - 2:00 PM PDT | Conv. Ctr. Room 2
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We present [1] a quantitative theory of the suppression of the optical linewidth due to charge fluctuation noise in a p–n diode, recently observed in Ref. 2. We connect the local electric field with the voltage across the diode, allowing for the identification of the defect depth from the experimental threshold voltage. Furthermore, we show that an accurate description of the decoherence of such spin centers requires a complete spin–1 formalism that yields a bi-exponential decoherence process, and predict how reduced charge fluctuation noise suppresses the spin center's decoherence rate. The material is based on work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Award Number DE-SC0019250. [1] Denis R. Candido and Michael E. Flatté, arXiv:2008.13289 [2] C. P. Anderson, A. Bourassa et al., Science 366, 1225 (2019).
11805-63
Author(s): Kimberley C. Hall, Ajan Ramachandran, Grant R. Wilbur, Dalhousie Univ. (Canada); Sabine O'Neal, Dennis G. Deppe, sdPhotonics, LLC (United States)
On demand starting 1 August 2021
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We report the demonstration of adiabatic rapid passage on single solid-state quantum emitters based on semiconductor quantum dots. By extending our earlier experiments employing femtosecond pulse shaping for rapid [1] and arbitrary [2,3] qubit rotations to the strong-driving regime, we demonstrate full suppression of decoherence tied to LA phonon coupling. Our results will support the development of single photon sources and distributed quantum networks using semiconductor quantum dots. [1] Mathew et al. Phys. Rev. B 90, 035316 (2014). [2] Gamouras et al. Nano Letters 13, 4666 (2013). [3] Mathew et al. Phys. Rev. B 92, 155306 (2015).
11805-64
Author(s): Peter Stano, RIKEN (Japan)
On demand starting 1 August 2021
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I present results on optimal phase estimation of a qubit, using a spin qubit in a gated semiconductor quantum dot as an example. I show how the optimal estimation can help protect the coherence of the current spin-qubit devices against slow noise (nuclear spin-noise in GaAs or quasi-static charge-noise in Si). I formulate optimal estimation as a minimization problem and discuss the entropy and the variance as possible figures of merit. I describe the classes of minimization strategies: local versus global and online versus offline. I finally present our algorithm which produces the optimal solution within the local(greedy)-offline class.
11805-65
Author(s): Yasuhiro H. Matsuda, The Institute for Solid State Physics, The Univ. of Tokyo (Japan)
On demand starting 1 August 2021
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Spins behave quantum mechanically in solids. If there are strong interactions between spins, the effective repulsion force constraints the behavior of spins and intriguing quantum phenomena such as a magnon crystal, Bose-Einstein condensation (BEC), and spin liquid, appear when a magnetic field whose Zeeman energy is comparable to the interaction strength is applied at low temperatures. In the present study, such magnetic field induced quantum phase transitions have been investigated using ultrahigh magnetic fields exceeding 100 T. Specifically, the magnon crystals in SrCu2(BO3)2, the magnon BEC in TlCuCl3, and the spin liquid in a-RuCl3 were observed. In addition to the pure spin systems, systems that possess a strong spin-lattice coupling exhibit more variety of phenomena including structural phase transitions in the ultrahigh fields: The spin state BEC in LaCoO3 and the insulator-metal transition in V1-xWxO2 have been recently studied in magnetic fields of up to 600 T.
11805-67
Author(s): Gerd Bacher, Univ. Duisburg-Essen (Germany)
On demand starting 1 August 2021
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Advances in chemical synthesis enable the design of nanocrystals with targeted architecture, functionalized by transition metal doping. As a consequence of pronounced exchange interactions between charge carriers and dopants, this class of materials combines optical, electronic and magnetic activity even up to room temperature. Ensemble doping leads to collective spin phenomena like optically and electrically triggered magnetization as well as spin fluctuations, probed down to the level of single quantum dots. We found strong anisotropy effects paving the path towards directed magnetic polaron formation. Incorporation of single magnetic impurities yield unique discoveries like huge zero-field exchange splittings, which allows probing the spin state of an individual atom, or digital magnetic doping in magic size nanocluster.
Session 18: Semiconductor Spintronics
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Author(s): Shinobu Ohya, Miao Jiang, Hirokatsu Asahara, Shoichi Sato, Masaaki Tanaka, The Univ. of Tokyo (Japan)
On demand starting 1 August 2021
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Spin-orbit torque (SOT) magnetization switching is an efficient method to control magnetization. In SOT switching, controlling a field-like torque strength is indispensable to reduce the critical current density; however, this is difficult because the field-like torque is intrinsic to the material system used. Here, we show that it can be suppressed in a spin-orbit ferromagnet single layer of (Ga,Mn)As by a current-induced Oersted field due to its strong Dresselhaus spin-orbit coupling and non-uniform current distribution. We obtained an extremely low switching current density of 4.6×10^4 A/cm^2, three orders of magnitude smaller than that observed in typical metal bilayers.
11805-70
Author(s): Konstantin Denisov, Mikhail Rakitskii, Igor Rozhansky, Ioffe Institute (Russian Federation)
On demand starting 1 August 2021
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In this work we argue that the electron skew scattering on paramagnetic impurities in non-magnetic semiconductors possesses a remarkable fingerprint, allowing us to differentiate it directly from other microscopic mechanisms of the emergent Hall response. We demonstrate theoretically that the exchange interaction between the impurity magnetic moment and itinerant carriers leads to the emergence of an electric Hall current persisting even at zero electron spin polarization. We describe two microscopic mechanisms behind this effect, and propose an essentially all-electric scheme based on a spin-injection ferromagnetic-semiconductor device, which allows one to reveal the effect of paramagnetic impurities on the Hall phenomena via the detection of the spin polarization-independent terms in the Hall voltage.
Session 19: Semiconductor Spintronics and Valleytronics
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Author(s): Keshav M. Dani, Okinawa Institute of Science and Technology Graduate Univ. (Japan)
On demand starting 1 August 2021
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About a decade ago, the discovery of monolayers of transition metal dichalcogenides opened a new frontier in the study of optically excited states in semiconductors. These materials exhibit a plethora of robust excitonic states, such as the optically accessible bright excitons, momentum- and spin-forbidden dark excitons, and hot excitons. In today’s talk, I will discuss studies in my lab of photoexcited two-dimensional semiconductors using time-resolved photoemission spectroscopy.
11805-72
Author(s): Priyabrata Mudi, Shailesh Kumar Khamari, Tarun Kumar Sharma, Raja Ramanna Ctr. for Advanced Technology (India)
On demand starting 1 August 2021
11805-73
Author(s): Boris Khots, Independent Researcher (United States); Dmitriy Khots, Consultant (United States)
On demand starting 1 August 2021
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This paper considers homomorphism ρ of the Lie group SU(2) to the Lie group SO(3) of all rotations of 3-dimensional Euclidean space from Observer’s Mathematics point of view. We proved here the following theorems: Theorem 1. In Observer’s Mathematics the probability of two-to-one transformation ρ of SU(2) to SO(3) is Lie groups homomorphism (representation) is less than 1. Theorem 2. The probability of two-to-one transformation ρ and spin-j transformation (j = 1) are equivalent in Observer’s Mathematics is less than 1.
Session 20: Tunneling Phenomena
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Author(s): Ron Jansen, A. Spiesser, Y. Fujita, H. Saito, National Institute of Advanced Industrial Science and Technology (Japan); S. Yamada, K. Hamaya, Osaka Univ. (Japan); S. Yuasa, National Institute of Advanced Industrial Science and Technology (Japan)
On demand starting 1 August 2021
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When a ferromagnet is in contact with a non-magnetic material, the exchange interaction extends into the non-magnetic material and converts it into an equilibrium ferromagnet. The effect is short range (decay length ~ 1 nm). Therefore, one typically uses a direct contact of the ferromagnetic and non-magnetic layers. Here, we demonstrate proximity exchange coupling across an MgO tunnel barrier, using Fe/MgO/silicon structures. By probing the effect of the exchange field on spin precession of the spin accumulation at the MgO/Si interface, we obtain the magnitude and direction of the exchange field and the dependence on MgO thickness and bias voltage.
11805-75
Author(s): Suyogya Karki, Vivian Rogers, The Univ. of Texas at Austin (United States); Sophia Chen, Cornell University (United States); Priyamvada Jadaun, The Univ. of Texas at Austin (United States); Daniel S. Marshall, TAE Technologies, Inc (United States), Arizona State Univ. (United States); Jean Anne C. Incorvia, The Univ. of Texas at Austin (United States)
On demand starting 1 August 2021
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Magnetic tunnel junctions (MTJs) show great promise for implementation in high-performance STT-MRAM and novel computing regimes such as magnetic logic and neuromorphic computing. However, a handful of material setbacks stand in the way of the adoption of leading MgO MTJs over other emerging technologies, such as Resistive-RAM junctions, in next-generation architectures. Here, we explore the properties of iron / scandium nitride (ScN) magnetoresistive junctions using density functional theory (DFT) and find ScN a promising barrier material given its novel electron symmetry filtering properties, high TMR, and low RA-product. Magnetoresistance ratios exceeding 1900% are enabled by Δ2’ symmetry filtering through the barrier, in addition to the traditional Δ1 symmetries observed in MgO MTJs. The electronic properties of the diffusive Fe/ScN interface are resolved, with predicted half-metallicity that could amplify MR in realistic low-power ScN devices.
11805-76
Author(s): Satoshi Iba, National Institute of Advanced Industrial Science and Technology (Japan); Yuzo Ohno, Univ. of Tsukuba (Japan)
On demand starting 1 August 2021
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Long-range spin transport at room temperature is one of the indispensable technologies for realizing spintronics devices. In this study, we have investigated electron spin relaxation time of (110)-oriented GaAs superlattice having tunnel-coupled quantum wells for both lateral and vertical spin transport. It was revealed that the spin relaxation time at room temperature was 0.7 ns, about 7 times longer than that of bulk GaAs which has been used for conventional spin transport layer of spin-controlled lasers. This finding provides a novel method of controlling the spin relaxation time at room temperature and indicates that the superlattice structures are promising for spin transport layers in semiconductor-based spintronics devices.
Session 21: Artificial Spin-Ice and Spin Textures
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Author(s): Benjamin Jungfleisch, Mojtaba T. Kaffash, Sergi Lendinez, Univ. of Delaware (United States)
On demand starting 1 August 2021
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The term “artificial spin ice” (ASI) refers to a class of magnetic metamaterials where magnetic domains can be mapped onto a spin-lattice model [1]. Here, we present broadband ferromagnetic resonance and Brillouin light scattering measurements of ASI and correlate the experimental findings with micromagnetic simulations. We focus on the angular-dependent spin dynamics of different types of ASI made of one single material [3-4] and bicomponent ASIs composed of two sub-lattices made of dissimilar materials [5]. Our results show that the interaction and the resonant dynamics in ASI can be tuned, not only by the field, geometry and orientation of the lattice, but also by the proper choice of the materials. [1] Sklenar et al., Solid State Phys. 70, 171-235 (2019), [2] Lendinez & Jungfleisch, J. Phys.: Condens. Matter 32, 013001 (2020), [3] Bang et al., Phys. Rev. Applied 14, 014079 (2020), [4] Kaffash et al., Phys. Rev. B 101, 174424 (2020), [5] Lendinez et al., arXiv:2010.03008 (2020).
11805-77
Author(s): Robert L. Stamps, Univ. of Manitoba (Canada)
On demand starting 1 August 2021
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Complex dynamics far from equilibrium in two dimensions can be explored in arrays of interacting nano-scale magnetic islands. We discuss how the fine details of how magnetic islands interact can lead to non-intuitive and often striking behaviour that is observable on macroscopic length and time scales. Results from nano-scale squid and Lorentz transmission electron microscopy imaging are analysed using models for thermal activation and Monte Carlo simulations. We find evidence for the emergence of effective anisotropies and surprising consequences for avalanche dynamics can be attributed to correlated, microscopic spin configurations that can arise within individual magnetic elements.
11805-78
Author(s): Alan Farhan, Aalto Univ. (Finland)
On demand starting 1 August 2021
11805-80
Author(s): Masahiro Sato, Ibaraki Univ. (Japan)
On demand starting 1 August 2021
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We theoretically study the high harmonic generation (HHG) in Kitaev spin liquids, comparing the HHG with those of ferromagnets and semiconductors. We find several new features can be observed in the HHG of the featureless Kitaev spin liquids. Our results would build a bridge between photo science and quantum spin liquids.
11805-81
Author(s): Gavin M. Macauley, Paul Scherrer Institut (Switzerland); Gary Paterson, Rair Macedo, Stephen McVitie, Univ. of Glasgow (United Kingdom); Robert Stamps, Univ. of Manitoba (Canada)
On demand starting 1 August 2021
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Artificial spin ices are arrays of correlated nano-scale magnetic islands that prove an excellent playground in which to study critical phenomena. In this contribution, we discuss how both geometry and the coupling of islands to external fields influence magnetic order. Using Lorentz transmission electron microscopy, we study a transition between antiferromagnetic and ferromagnetic order across a continuum of spin ice geometries. We show how emergent anisotropies can arise in field-driven processes and how relaxation timescales can be adjusted locally within arrays through a coupling to a site-specific bias field. Our work demonstrates artificial spin ice as an excellent testbed in which to probe non-equilibrium phenomena in low-dimensional systems.
Session 22: New Materials, Structures, and Systems
In person: 2 August 2021 • 2:00 PM - 3:00 PM PDT | Conv. Ctr. Room 2
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Author(s): Kenneth Burch, Boston College (United States)
In person: 2 August 2021 • 2:00 PM - 2:30 PM PDT | Conv. Ctr. Room 2
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Two-dimensional (2d) nano-electronics, plasmonics, spintronics and emergent phases require clean and local charge control, calling for layered, crystalline acceptors or donors. Here I will describe how the Relativistic Mott Insulating state of RuCl3, a 2D antiferromagnet, provides a new opportunity to introduce modulation doping into 2D materials. Specifically, we demonstrate and optimize this charge transfer with extensive Raman, photovoltage, and electrical conductance measurements combined with ab initio calculations. Also, we find the doping is exceptionally local, can occur through hBN, works with various exfoliated, CVD, and MBE materials. Time permitting, I will discuss new opportunities this opens for nanoplasmonic, optoelectronics, and correlated phases.
11805-84
Author(s): Robert Streubel, Univ. of Nebraska-Lincoln (United States); Xuefei Wu, Xubo Liu, Beijing Univ. of Chemical Technology (China); Thomas P. Russell, Univ. of Massachusetts Amherst (United States)
In person: 2 August 2021 • 2:30 PM - 3:00 PM PDT | Conv. Ctr. Room 2
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Magnetic micro and nanostructures resembling macrospins have, to date, been lithographically patterned and fixed to a predefined 2D or, most recently, 2.5D layout. I will present an alternate route facilitating interfacial self-assembly and jamming of superparamagnetic nanoparticles at curved liquid-liquid interfaces to create macrospin systems [1,2]. The mechanical jamming of superparamagnetic nanoparticles is key to freeze both structural and magnetic short-range order and transform the paramagnetic ensemble into a ferromagnetic systems with remanent magnetization and rigid microscopic shape. We use hydrodynamics experiments to probe how the magnetization of ferromagnetic liquid droplets and their response to external stimuli can be tuned by chemical, structural and magnetic means. Numerical modeling using molecular dynamics and mircomagnetic simulations, usher a path toward nanopatterning structured liquids. [1] Science 365, 264 (2019). [2] Materials 13, 2712 (2020).
11805-83
Author(s): Joel Kuttruff, University of Konstanz (Germany), Univ. du Luxembourg (Luxembourg); Gaia Petrucci, University of Pisa (Italy); Yingqi Zhao, Marzia Iarossi, Istituto Italiano di Tecnologia (Italy); Esteban Pedrueza Villalmanzo, University of Gothenburg (Sweden); Giuseppe Strangi, Case Western Reserve University (United States); Alexandre Dmitriev, University of Gothenburg (Sweden); Francesco De Angelis, Istituto Italiano di Tecnologia (Italy); Daniele Brida, Univ. du Luxembourg (Luxembourg); Francesco Pineider, University of Pisa (Italy); Nicolò Maccaferri, Univ. du Luxembourg (Luxembourg)
On demand starting 1 August 2021
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Hyperbolic nanoparticles provide a versatile platform to widely tune light-matter interactions. Active nanophotonics can be realized by controlling the optical properties of materials with external magnetic fields. Here, we explore the influence of optical anisotropy on the magneto-optical response of hyperbolic nanoparticles across the visible and near infrared spectral range. By using a perturbative approach, we establish a model where the magneto-optical activity of the system is described in terms of the coupling of fundamental electric and magnetic dipole modes, which are induced by the hyperbolic dispersion, with a static magnetic field. Finally, an analytical model is established in the framework of Mie theory to describe the magneto-optical response and identify the contribution of electric and magnetic modes to the total spectrum.
11805-85
Author(s): Oleg I. Rabinovich, Sergey Marenkin, National Univ. of Science and Technology MISIS (Russian Federation); Alex Ril, V. Kozlov, National Univ. of Science and Technology MISIS (Russian Federation)
On demand starting 1 August 2021
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Magnetically ordered granular structures are an alternative to superlattices for spintronic devices. For magnetically ordered granular structure such components were chosen: a narrow-gap semiconductor with high electron conductivity - Cd3As2 and ferromagnet - MnAs. The Cd3As2-MnAs system samples were synthesized and magnetic calorimetric properties were investigated depending on the MnAs ferromagnetic phase composition and dimension. The coercive force in it was increased by 8 times, the Curie temperature increased by 30°. The magnetically ordered granular structure creation with optimal parameters, the eutectic composition of the Cd3As2-MnAs system, synthesized under high supercooling, for example, by spinning, seems to be more efficient.
11805-86
Author(s): Oleg I. Rabinovich, Sergey Marenkin, Alex Ril, National Univ. of Science and Technology MISIS (Russian Federation)
On demand starting 1 August 2021
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Structures based on ferromagnets and semiconductors are promising for spintronic devices. Cd3As2-MnAs subsystem, which is a component of the Cd3As2-MnAs-CdAs2 ternary system is chosen as investigation sample. By XRD, DTA and microstructural investigation it was detected that the ternary system is limited by three quasi-binary cross sectional view Cd3As2 - MnAs, CdAs2 - MnAs, and Cd3As2 - CdAs2 eutectic type. For CdAs2-MnAs system, it was obtained samples crystallized at a high cooling rate with nanosized inclusions (ferromagnetic phase ≤40 nm MnAs). The electrical and magnetic properties investigation show that they are ferromagnets with TCurie = 340 °С and high magnetoresistance.
11805-104
Author(s): Thomas Guillet, ICN2 (Spain); Giulio Gentille, CEA-Grenoble (France); Regina Galceran, Juan F. Sierra, Marius Costache, ICN2 (Spain); Matthieu Jamet, Frédéric Bonell, CEA-Grenoble (France); Sergio O. Valenzuela, ICN2 (Spain)
On demand starting 1 August 2021
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Topological insulators (TI) have gained much interest in the field of spintronics for the generation of pure spin currents. Indeed, three-dimensional TIs are predicted to host exotic properties like topologically protected surface states (TSS), which show Dirac-like band dispersion and spin-momentum locking [1]. One of the main strategies is to take advantages of the spin polarization of the TSSs to manipulate the magnetization of an adjacent ferromagnetic thin film (FM) using the spin-orbit torque (SOT) mechanism [2]. In the past few years, the community attempted to replace the traditional heavy metals by a TI in order to enhance the SOT efficiency with limited success. It now appears that the interface sharpness and the high chemical affinity between Bi-based TIs and classical 3d FMs is a major hurdle to reach the predicted breakthrough in magnetization switching power-efficiency [3]. The emergence of ferromagnetism in two dimensions in 2017, which started a new field in condensed matter physics, could bring a solution to this issue.The van der Waals (vdW) nature of the interaction between the TI and the 2D-FM should limit chemical reactions, interface intermixing and hybridization of state between the two layers.
Live Remote Keynote Session: Nanoscience + Engineering Applications I
In person: 3 August 2021 • 11:30 AM - 12:30 PM PDT | Conv. Ctr. Room 6A
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Author(s): Shanhui Fan, Stanford Univ. (United States)
In person: 3 August 2021 • 11:30 AM - 12:00 PM PDT | Conv. Ctr. Room 6A
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We show that wavevector-space metasurface can be used to achieve non-trivial correlation between the frequency and the momentum of light. As applications we demonstrate squeezing of free space, generation of meron textures, and creation of the three dimensional light bullets.
11796-80
Author(s): Thomas F. Krauss, Univ. of York (United Kingdom)
In person: 3 August 2021 • 12:00 PM - 12:30 PM PDT | Conv. Ctr. Room 6A
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The challenge for biosensors is to achieve high performance and multiple functionalities at low cost, which includes the source and readout instrumentation. Here, we describe a sensor modality utilizing guided mode resonances that can detect multiple markers for infection, that combines the sensor chip and spectrometer in a single chip and that can achieve a limit of detection as low as 1pg/ml. This performance is equivalent or better than laboratory-based techniques yet the sensor and instrumentation can be made entirely from low-cost components.
Live Remote Keynote Session: Nanoscience + Engineering Applications II
In person: 3 August 2021 • 2:00 PM - 3:00 PM PDT | Conv. Ctr. Room 6A
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Spintronics with bacteria (Keynote Presentation)
Author(s): Benjamin Zingsem, Univ. Duisburg-Essen (Germany); Thomas Feggeler, Lawrence Berkeley National Laboratory (United States); Michael Winklhofer, Carl von Ossietzky University of Oldenburg (Germany); Michael Farle, Univ. Duisburg-Essen (Germany)
In person: 3 August 2021 • 2:00 PM - 2:30 PM PDT | Conv. Ctr. Room 6A
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Spin wave logic circuits using quantum oscillations of spins (magnons) as carriers of information have been proposed for next generation computing with reduced energy demands and the benefit of easy parallelization. Current realizations of magnonic devices have micrometer sized patterns. Here we demonstrate the feasibility of biogenic nanoparticle chains as the first step to truly nanoscale magnonics at room temperature. Our measurements on magnetosome chains (ca 12 magnetite crystals with 35 nm particle size each), combined with micromagnetic simulations, show that the topology of the magnon bands, namely anisotropy, band deformation, and band gaps are determined by local arrangement and orientation of particles, which in turn depends on the genotype of the bacteria. Our biomagnonic approach offers the exciting prospect of genetically engineering magnonic quantum states in nanoconfined geometries. By connecting mutants of magnetotactic bacteria with different arrangements of magnetite
11805-68
Author(s): Masashi Shiraishi, Kyoto Univ. (Japan)
In person: 3 August 2021 • 2:30 PM - 3:00 PM PDT | Conv. Ctr. Room 6A
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Gate-tunable spin-orbit interaction (SOI) and its related phenomena have been a new aspects of spintronics and spin-orbitronics. In this presentation, recent progress of gate modulation of the inverse spin Hall effect [1,2], its reciprocal effect [3] and spin lifetime anisotropy [3] in solids by a gate electric field will be introduced and discussed. [1] S. Dushenko, M. Shiraishi et al., Nature Commun. 9, 3118 (2018). [2] S. Yoshitake, M. Shiraishi et al., Appl. Phys. Lett. 117, 092406 (2020). [3] R. Ohshima, M. Shiraishi et al., submitted. [4] S. Lee, M. Shiraishi et al., submitted.
Conference Chair
Lab. des Solides Irradiés, Ecole Polytechnique (France)
Conference Chair
Ecole Polytechnique (France)
Conference Chair
Northwestern Univ. (United States)
Conference Co-Chair
Unité Mixte de Physique CNRS/Thales (France)
Program Committee
Claire Baraduc
CEA-Grenoble (France)
Program Committee
Franco Ciccacci
Politecnico di Milano (Italy)
Program Committee
Russell P. Cowburn
Univ. of Cambridge (United Kingdom)
Program Committee
Los Alamos National Lab. (United States)
Program Committee
Unité Mixte de Physique CNRS/Thales (France)
Program Committee
Hanan Dery
Univ. of Rochester (United States)
Program Committee
Univ. of Victoria (Canada)
Program Committee
Univ. Montpellier 2 (France)
Program Committee
The Univ. of Iowa (United States)
Program Committee
Joseph S. Friedman
The Univ. of Texas at Dallas (United States)
Program Committee
Pietro Gambardella
ETH Zurich (Switzerland)
Program Committee
Unité Mixte de Physique CNRS/Thales (France)
Program Committee
Ruhr-Univ. Bochum (Germany)
Program Committee
Unité Mixte de Physique CNRS/Thales (France)
Program Committee
Technion-Israel Institute of Technology (Israel)
Program Committee
Institute of Physics of the CAS, v.v.i. (Czech Republic)
Program Committee
Virginia Polytechnic Institute and State Univ. (United States)
Program Committee
Mathias Klaui
Univ. Konstanz (Germany)
Program Committee
Daniel Lacour
Institut Jean Lamour (France)
Program Committee
U.S. Naval Research Lab. (United States)
Program Committee
Aurélien Manchon
King Abdullah Univ. of Science and Technology (Saudi Arabia), CINaM, Aix-Marseille Univ, CNRS (France)
Program Committee
INSA - Univ. of Toulouse (France)
Program Committee
Laurens W. Molenkamp
Julius-Maximilians-Univ. Würzburg (Germany)
Program Committee
Hiro Munekata
Tokyo Institute of Technology (Japan)
Program Committee
Hans T. Nembach
National Institute of Standards and Technology (United States)
Program Committee
The Univ. of Tokyo (Japan)
Program Committee
Vlad Pribiag
Univ. of Minnesota, Twin Cities (United States)
Program Committee
Institut d'Électronique Fondamentale (France)
Program Committee
Nicolas Rougemaille
Institut NÉEL (France)
Program Committee
Georg Schmidt
Martin-Luther-Univ. Halle-Wittenberg (Germany)
Program Committee
Univ. of California, Riverside (United States)
Program Committee
Univ. du Maine (France)
Program Committee
Applied Materials, Inc. (United States)
Program Committee
Univ. of Nebraska-Lincoln (United States)
Program Committee
U.S. Naval Research Lab. (United States)
Program Committee
Univ. Regensburg (Germany)
Program Committee
Igor Zutic
Univ. at Buffalo (United States)