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Conference 12205

# Spintronics XV

21 - 25 August 2022
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• 1: THz Spintronics I
• 2: Topological Spintronics I
• 3: Topological Spintronics II
• 4: THz Spintronics II
• 5: MRAMs and Sensors
• 6: MRAMs and Spintronics Devices
• 7: Neuromorphic Computing
• 8: Van der Waals Spintronics
• 9: Spin-Hall Effect and Spin-Orbit Torque
• 10: Coherence and Ballistic Transport
• 11: Spin Lasers
• 12: Spin Photonics
• 13: Superconducting and Voltage-Controlled Spintronics
• 14: Voltage-Controlled Spintronics
• 15: Magneto Optics and Imaging
• 16: Nanomagnetism and Magnonics
• 17: Orbital Torque and Spin-Seebeck Effect
• 18: Quantum Spintronics Theory
• Poster Session
• Sunday Evening Plenary
• Nanoscience + Engineering Plenary
Information

• Submissions accepted through 5-July

Call for Papers Flyer
Session 1: THz Spintronics I
12205-2
Author(s): Yoshua Hirai, Naotaka Yoshikawa, Hana Hirose, Masashi Kawaguchi, Masamitsu Hayashi, The Univ. of Tokyo (Japan); Ryo Shimano, The Univ. of Tokyo (Japan), Cryogenic Research Ctr., The Univ. of Tokyo (Japan)
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We investigated the terahertz (THz)-wave emission from thin films of bismuth, a well-known Dirac electron system, by circularly polarized femtosecond pulse excitation. We identified that the observed helicity-dependent THz-wave emission has a bulk origin and is a consequence of the large ISHE and long spin diffusion length of bismuth. In the presentation, we will introduce experimental results leading to this conclusion. Our results demonstrate a new functionality of bismuth as a platform for THz spintronics. We will also discuss the ultrafast charge carrier and spin dynamics in photoexcited bismuth from the time-resolved measurements of the THz-wave emission.
12205-3
Author(s): Enzo Rongione, Unité Mixte de Physique CNRS/Thales, Univ. Paris-Saclay (France), Lab. de Physique de l'Ecole Normale Supérieure (France), CNRS (France); Laëtitia Baringthon, Unité Mixte de Physique CNRS/Thales, Univ. Paris-Saclay (France), Synchrotron SOLEIL, Cassiopée beamline (France); Sotirios Fragkos, Institute of Nanoscience and Nanotechnology, National Ctr. for Scientific Research "Demokritos" (Greece), Univ. of West Attica (Greece); Jacques Hawecker, Lab. de Physique de l'Ecole Normale Supérieure (France), Univ. PSL (France), CNRS (France); Thi-Huong Dang, Unité Mixte de Physique CNRS/Thales, Univ. Paris-Saclay (France); Evangelia Xenogiannopoulou, Polychronis Tsipas, Institute of Nanoscience and Nanotechnology, National Ctr. for Scientific Research “Demokritos" (Greece); Patrick Le Fèvre, Synchrotron SOLEIL, Cassiopée beamline (France); Nicolas Reyren, Unité Mixte de Physique CNRS/Thales, Univ. Paris-Saclay (France); Gilles Patriarche, Aristide Lemaître, Ctr. de Nanosciences et de Nanotechnologies, Univ. Paris-Saclay, CNRS (France); Athanasios Dimoulas, Institute of Nanoscience and Nanotechnology, National Ctr. for Scientific Research “Demokritos" (Greece); Romain Lebrun, Jean-Marie George, Unité Mixte de Physique CNRS/Thales, Univ. Paris-Saclay (France); Sukhdeep Dhillon, Lab. de Physique de l'Ecole Normale Supérieure (France), Univ. PSL (France), CNRS (France); Henri Jaffrès, Unité Mixte de Physique CNRS/Thales, Univ. Paris-Saclay (France)
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We report the terahertz (THz) emission from Bi1-xSbx/Co and Bi2SnTe4/Co bilayers including nanometer-thin ferromagnetic layer as spin-injectors and Bi1-xSbx and Bi2SnTe4 topological insulators (TI) from the Bi family grown by molecular beam epitaxy. Using THz emission spectroscopy, an efficient dynamical spin-to-charge conversion in the sub-picosecond timescale is demonstrated in these heterostructures with an output THz amplitude sizeable compared to reference metallic spintronic THz emitters. We investigate TI thickness dependence and azimuthal crystalline orientation dependence on the THz emission which are both in line with interfacially-mediated interconversion. We show that a strong reminiscent THz signal at the limit of small TI thickness is explained by a spin-charge interconversion occurring at the level of the first planes of their interface in contact with Co. This strongly suggests a spin-charge interconversion via inverse Rashba-Edelstein effect (IREE) onto spin-locked TI’s interface states.
12205-4
Author(s): Matthias Benjamin Jungfleisch, Univ. of Delaware (United States); Vinay Sharma, Morgan State Univ. (United States); Weipeng Wu, Univ. of Delaware (United States); Prabesh Bajracharya, Morgan State Univ. (United States); Duy Quang To, Univ. of Delaware (United States); Anthony Johnson, Morgan State Univ. (United States); Anderson Janotti, Univ. of Delaware (United States); Garnett W. Bryant, National Institute of Standards and Technology (United States); Lars Gundlach, Univ. of Delaware (United States); Ramesh C. Budhani, Morgan State Univ. (United States)
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Three-dimensional (3D) topological insulators (TI) with large spin Hall conductivity have emerged as potential candidates for spintronic applications. Here, we report spin to charge conversion in bilayers of amorphous ferromagnet Fe78Ga13B9 (FeGaB) and 3D TI Bi85Sb15 (BiSb) activated by two complementary techniques: spin pumping and ultrafast spin-current injection. The spin pumping parameters derived from inverse spin Hall effect (ISHE) measurements are consistent with the results of femtosecond light-pulse induced THz emission. These measurements are successfully verified using theoretical calculations of thickness-dependent spin Hall conductivity of BiSb thin films based on a tight-binding model.
Session 2: Topological Spintronics I
12205-5
Author(s): Dimitrie Culcer, James Cullen, The Univ. of New South Wales (Australia); Rhonald Burgos Atencia, Univ. del Sinú (Colombia)
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Spin torques at topological insulator/ferromagnet interfaces are being researched for computing applications, yet the relative contributions stemming from the bulk and surface states are poorly understood. I will discuss bulk spin torques and demonstrate that: (i) There is no bulk spin-Hall effect in the absence of a magnetization; (ii) A homogeneous magnetization experiences no torque; (iii) An inhomogeneous spin-orbit torque arises due to the magnetization gradient near the interface. It has similar magnitudes for out-of-plane and in-plane magnetizations, which is an experimental smoking gun for bulk spin torques. I will discuss implications for experiment.
12205-6
Author(s): Alexey Belyanin, Texas A&M Univ. (United States)
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Materials with Dirac and Weyl fermions have highly unusual magnetooptical properties which can be utilized in compact optoelectronic devices and circuits. Moreover, magnetooptical spectroscopy can provide a cleaner way of studying topological properties of their electron states as compared to transport measurements. I will discuss several examples illustrating these points: an extremely high optical nonlinearity in Landau-quantized graphene and its device applications; optical anisotropy and optical Hall effect in magnetic Weyl semimetals; inverse Faraday effect in graphene and topological materials; and unique properties of magnetopolaritons in Dirac and Weyl semimetals in a strong magnetic field.
12205-7
Author(s): Edwin Fohtung, Xiaowen Shi, Rensselaer Polytechnic Institute (United States); Dmitry Karpov, European Synchrotron Radiation Facility (France)
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Observations of magnetic domains and domain walls are essential for understanding switching characteristics in magnetic devices. Here, we demonstrate that the use of optical birefringence [1], coupled with a first-order magneto-optic effect (Kerr effect), allows the visualization of magnetic domains in transparent magnetic materials. We utilize a field-modulation interaction of polarized light with the material to develop a technique that captures images of magnetic domains in real space and their scattered diffraction patterns in Fourier space. With the use of a complementary metal-oxide-semiconductor (CMOS) area image sensor, the phase of the modulated wavefront can be reconstructed using iterative phase retrieval algorithms from the recorded diffraction patterns to demonstrate magnetic spin textures which can be controlled with an external magnetic field. The observed images are consistent with magnetic force microscopy and traditional MOKE images of transparent single-crystal Yttrium iron garnet (YIG) Y3Fe5O12 thin films. This approach can be applied to other transparent crystals. such as ferroelectrics. [1] D. Karpov et al, Birefringent coherent diffractive imaging. Proceedings Volume 9931, Spintronics IX; 99312T (2016) https://doi.org/10.1117/12.2235865
12205-8
Author(s): Salvatore Teresi, Jean-Philippe Attané, Laurent Vila, Maxen Cosset-Cheneau, CEA (France), Spintec (France); Albert Fert, Unité Mixte de Physique CNRS/Thales, Univ. Paris Saclay (France); Tristan Meunier, Institut NÉEL, CNRS (France); Philippe Ballet, CEA-LETI (France); Yann-Michel Niquet, Interdisciplinary Research Institute of Grenoble, CEA (France); Candice Thomas, CEA-LETI (France); Thomas Guillet, Cécile Grezes, Paul Noël, Jules Papin, CEA (France), Spintec (France); Jing Li, CEA-LETI (France); Yu Fu, CEA (France), Spintec (France)
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Spin-orbit effects appearing in topological insulators (TI) and at Rashba interfaces are currently revolutionizing how we can manipulate spins and have led to several newly discovered effects, from spin-charge interconversion and spin-orbit torques to novel magnetoresistance phenomena. In particular, a puzzling magnetoresistance has been evidenced, bilinear in electric and magnetic fields. Here, we report the observation of bilinear magnetoresistance (BMR) in strained HgTe, a prototypical TI. We show that both the amplitude and sign of this BMR can be tuned by controling, with an electric gate, the relative proportions of the opposite contributions of opposite surfaces. At magnetic fields of 1 T, the magnetoresistance is of the order of 1 % and has a larger figure of merit than previously measured TIs. We propose a theoretical model giving a quantitative account of our experimental data. This phenomenon, unique to TI, offer novel opportunities to tune the electrical response of surface states for spintronics.
Session 3: Topological Spintronics II
12205-9
Author(s): Oliver Rader, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany)
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Magnetically doped topological insulators enable the quantum anomalous Hall effect. Stoichiometric systems of AB2C4 stoichiometry are considered promising but MnBi2Te4 is antiferromagnetic. MnSb2Te4 has been predicted to be antiferromagnetic as well and topologically trivial but we show that spin- and angle-resolved photoemission reveal a clear Dirac cone as sign of a topological insulator. Moreover, it is ferromagnetic with a high Curie temperature of up to 50 K, i. e., two times larger than the Néel temperature of the related MnBi2Te4. The reason for these properties is found in a 5% excess Mn as detailed calculations show.
12205-10
Author(s): Connie H. Li, Mehmet A. Noyan, Jisoo Moon, Olaf van 't Erve, Enrique D. Cobas, U.S. Naval Research Lab. (United States); Mark I. Lohmann, U.S. Naval Research Lab (United States); Xiaohang Zhang, Berry T. Jonker, U.S. Naval Research Lab. (United States)
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Current-generated spin in topological insulators (TIs) has been shown to efficiently switch FM magnetization via spin-orbit torque (SOT) with much lower critical currently densities. However, TI bulk are often degenerately doped and can shunt current from the surface states. Here we demonstrate SOT switching from bulk-insulating Bi2Se3, obtained by growth on BiInSe/In2Se3 buffer layers by MBE, with significantly reduced critical current density than conventional “bulk-conducting” Bi2Se3. We further grew epitaxial In2Se3 tunnel barriers on Bi2Se3, and demonstrate its spin sensitivity, towards further minimize current shunting through the FM metal and overall power consumption for magnetization switching.
12205-12
Author(s): Jukka Vayrynen, Purdue Univ. (United States)
Session 4: THz Spintronics II
12205-13
Author(s): Igor V. Rozhansky, Konstantin Denisov, Ioffe Institute (Russian Federation); Igor Zutic, Univ. at Buffalo (United States)
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We consider a spin-light coupling in heterostructures consisting of graphene-like 2D Dirac materials with proximity induced magnetic interaction and spin-orbit coupling (SOC). The combination of exchange and spin-orbit coupling opens a possibility for radiative transitions between the spin split states corresponding to THz range. We present a theoretical model describing radiation absorption and emission combined with spin and charge kinetics in a graphene system proximitized by a magnetic layer with induced exchange and Rashba-type SOC. The obtained results allow us to come up with a theoretical proposal of a THz detector and a THz emitter utilizing the studied physical mechanism.
12205-14
Author(s): Rudolf Bratschitsch, Westfälische Wilhelms-Univ. Münster (Germany)
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The recent invention of spintronic THz emitters has attracted a lot of attention due to their high power, broadband emission, and easy fabrication. They commonly consist of nanometer-thin bilayers of a magnetic (M) and a nonmagnetic (NM) metal film and rely on the inverse spin Hall effect. In my talk, I will present our recent results on bilayer M/NM spintronic emitters based on magnetic alloys, such as GdFe or CoFe, and Pt as the NM layer. Furthermore, functional multilayer spintronic THz emitter systems, which can be conveniently switched on and off, will be presented.
12205-15
Author(s): Sachin Krishnia, Enzo Rongione, Vincent Cros, Sophie Collin, Jean-Marie George, Unité Mixte de Physique CNRS/Thales (France); Sukhdeep Dhillon, Univ. PSL (France), Lab. de Physique de l'Ecole Normale Supérieure (France); Juliette Mangeney, Jerome Jerome, Lab. de Physique Statistique de l'ENS (France); Henri-Yves Jaffrès, Unité Mixte de Physique CNRS/Thales (France)
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Control of interfaces at nanometer scale in spintronic heterostructures has become vital to engineer efficient spin-orbit torques and THz emission properties. In this study, we propose the use of optimized Au:W based spin-sink materials to reduce the use of thick Pt layers in order to enhance the spin-current injection into adjacent ferromagnets. We demonstrate the use of optimized AuW alloy as a spin-sink material with different W content in Co/Pt/AuW series of samples. We observe a clear enhancement of spin injection efficiency at low Pt thickness down to 2nm by using second correlated harmonic voltage measurements and THz emission spectroscopy.
12205-16
Author(s): Stefan Mathias, Georg-August-Univ. Göttingen (Germany)
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The ultimate speed limit for all-optical spin manipulation requires control schemes on the timescale of the laser excitation pulse. In our work, we provide experimental evidence of such a direct, ultrafast and coherent spin transfer between distinct magnetic subsystems in ferromagnetic Ni-Fe alloys and Heusler compounds. Our experimental findings are fully supported by time dependent density functional theory simulations and, hence, suggests the possibility of coherently controlling spin dynamics on sub-femtosecond timescales.
12205-17
Author(s): Vivek Unikandanunni, Stockholm Univ. (Sweden); Rajasekhar Medapalli, Lancaster Univ. (United Kingdom); Marco Asa, Politecnico di Milano (Italy); Edoardo Albisetti, Politecnico di Milano (Italy); Daniela Petti, Riccardo Bertacco, Politecnico di Milano (Italy); Eric Fullerton, Univ. of California, San Diego (United States); Stefano Bonetti, Stockholm Univ. (Sweden), Univ. Ca' Foscari di Venezia (Italy)
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We investigate the spin dynamics driven by terahertz magnetic fields in epitaxial thin films of cobalt in its three crystalline phases. The terahertz magnetic field generates a torque on the magnetization which causes it to precess for about 1 ps, with a sub-picosecond temporal lag from the driving force. Then, the magnetization undergoes natural damped THz oscillations at a frequency characteristic of the crystalline phase. We describe the experimental observations solving the inertial Landau-Lifshitz-Gilbert equation. Using the results from the relativistic theory of magnetic inertia, we find that the angular momentum relaxation time is the only material parameter needed to describe all the experimental evidence. Our experiments suggest a proportionality between angular momentum relaxation time and the strength of the magneto-crystalline anisotropy.
Session 5: MRAMs and Sensors
12205-18
Author(s): Hideo Ohno, Shunsuke Fukami, Tohoku Univ. (Japan)
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Big data generated by Internet-of-Things (IoT) sensors and devices along with AI is changing the society we live in, allowing us to better understand and manage the world. Both IoT and AI require low energy information handling. For example, IoT devices are much better if it does not require a battery (i.e. energized by energy harvesting) and AI is known to be power-hungry calling for a means to drastically reduce the power for its ubiquitous use. Spintronics nonvolatile device, magnetic tunnel junction (MTJ), has been shown to reduce the operation power of a CMOS-based microprocessor by up to two orders of magnitude, suitable for IoT purposes and other applications. MTJs have also been shown to be scalable down to 2.3 nm without resorting to new materials, a significant advantage along with their high thermal stability, high endurance, and low voltage operation. Moreover, new computing schemes are emerging, where one expects to have higher performance than relying solely on silicon-based digital processing. One of the approaches is neuromorphic computing; we have made proof-of-concept spintronics devices for artificial synapses as well as neurons for neuromorphic applications. Another approach utilizes less stable MTJs for a novel form of computing, probabilistic computing, to address optimization problems: One can formulate integer factorization as an optimization problem in such a way that the most preferred state in terms of energy gives the factorized result. The time scale involved in these probabilistic MTJs is also discussed. If time allows, I will touch upon synthetic antiferromagnetic skyrmions for information carriers
12205-19
Author(s): Han K. Lee, Everspin Technologies, Inc. (United States)
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We present an overview of Everspin’s proprietary Spin-Transfer Torque (STT) MRAM technology. We have optimized our perpendicular MTJ STT-MRAM technology to achieve high-speed reliable switching over the temperature range of -40°C to +85°C with data retention of more than 10 years at +105°C and endurance of greater than 1e15 cycles at -40°C. This advanced STT-MRAM technology has been deployed in commercially available 1Gb ST-DDR4 stand-alone memory and low-latency 64Mb serial peripheral interface (SPI) STT-MRAM products, both integrated on 28 nm CMOS technology.
12205-20
Author(s): Ricardo C. Sousa, Daniel S. Hazen, Nuno Caçoilo, Bruno M. S. Teixeira, Alvaro Palomino Lopez, Olivier Fruchart, David Salomoni, Stéphane Auffret, Laurent Vila, Ioan-Lucian Prejbeanu, Liliana D. Buda-Prejbeanu, Bernard Dieny, Spintec, Univ. Grenoble Alpes (France), CEA (France), CNRS (France)
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Magnetic tunnel junctions with perpendicular magnetic anisotropy for Magnetic Random Access Memory need to combine high speed and low critical switching current. Higher spin transfer torque (STT) write efficiency is required. This can be achieved introducing a switchable assistance layer, which can be designed to maximize the STT efficiency independently of the switching direction. At the same time, the assistance layer also increases the retention in standby. The reversal process was confirmed with time-resolved measurements. The outlook for scaling to the sub-20 nm diameter range will also be reviewed looking at STT driven switching in perpendicular shape anisotropy cells.
12205-21
Author(s): Azad Naeemi, Piyush Kumar, Georgia Institute of Technology (United States); Yu-Ching Liao, Intel Corp. (United States); Siri Narla, Georgia Institute of Technology (United States)
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This paper presents a co-design framework for magnetic materials, devices, and memory arrays based on a hierarchy of physical models. Two major categories of devices are considered: spin-orbit-torque (SOT) and magnetoelectric (ME) random access memories. Experimentally validated/calibrated physical models and circuit compatible compact models for such devices are presented and used for cross-layer optimization of memory arrays. The application of these devices for compute-in-memory is also discussed and novel SOT and ME based cell designs for ternary content-addressable memories (TCAM) are presented. These TCAM cells are benchmarked against their SRAM and Fe-FET counterparts using a comprehensive modeling and benchmarking framework.
Session 6: MRAMs and Spintronics Devices
12205-22
Author(s): Thomas D. Boone, Western Digital Corp. (United States)
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Spin Transfer Torque (STT) MRAM is a very attractive enabling technology for space and defense applications due to its versatility (NVM to SRAM like performance), wide operating temperature range, high density and radiation tolerance. In this presentation we will review the promise of state-of-the-art STT-MRAM and its potential impact on current and future space applications. Included will be a thorough review of recent rad-effects characterization results for STT-MRAM. More exotic spintronic technology such as Spin Orbit Torque (SOT) MRAM and Voltage Controlled Magnetic Anisotropy (VCMA) MRAM will be discussed and considered for their specific benefits in rad-hard applications.
12205-23
Author(s): Dafiné Ravelosona, Spin-ION Technologies (France), CNRS (France), Univ. Paris Saclay (France)
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We have developed new manufacturing processes based on ion irradiation to tailor the structural properties of ultra-thin magnetic films and spintronic devices at atomic level and improve their performances. The key feature of the technology is the post-growth control at the atomic scale of structural properties and the corresponding magnetic properties. When realized through a mask this technology allows lateral modulation of magnetic properties without any physical etching. In this talk, we will show a few important results that suggest a pathway to optimize the performances of future generation of spintronic devices using ion irradiation.
12205-24
Author(s): Andreas Bahr, Christian-Albrechts-Univ. zu Kiel (Germany)
12205-25
Author(s): Martin Bowen, Institut de Physique et de Chimie des Matériaux de Strasbourg (France)
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I will present a novel concept that blends spintronics and quantum thermodynamics to generate electricity. This concept is invoked to explain our experimental observations of electrical generation across oxide and molecular spintronic devices that comprise paramagnetic centers sandwiched between electrodes with full transport spin polarization. The presence of so-called quantum resources, leading to a source of work of quantum origin called ergotropy, appears to be manifest in sub-kBT spectral features, as well in an apparent signature of a phase transition of the spin fluctuations on the paramagnetic centers. I will discuss our present research tracks to better understand this spintronic quantum engine. General info may also be found at www.spinengine.tech.
Session 7: Neuromorphic Computing
12205-26
Author(s): Jonathan M. Goodwill, National Institute of Standards and Technology (United States); Nitin Prasad, National Institute of Standards and Technology (United States), Univ. of Maryland (United States); Brian D. Hoskins, Matthew W. Daniels, National Institute of Standards and Technology (United States); Advait Madhavan, National Institute of Standards and Technology (United States), Univ. of Maryland (United States); Lei Wan, Tiffany S. Santos, Michael Tran, Jordan A. Katine, Patrick M. Braganca, Western Digital Corp. (United States); Mark D. Stiles, Jabez McClelland, National Institute of Standards and Technology (United States)
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Magnetic tunnel junctions (MTJs) provide an attractive platform for implementing neural networks because of their simplicity, nonvolatility and scalability. In a hardware realization, however, device variations, write errors, and parasitic resistance will generally degrade performance. To quantify such effects, we perform experiments on a 2-layer perceptron constructed from a 15 × 15 passive array of MTJs, examining classification accuracy and write fidelity. Despite imperfections, we achieve accuracy of up to 95.3 % with proper tuning of network parameters. The success of this tuning process shows that new metrics are needed to characterize and optimize networks reproduced in mixed signal hardware.
12205-27
Author(s): Naimul Hassan, Alexander J. Edwards, The Univ. of Texas at Dallas (United States); Dhritiman Bhattacharya, Georgetown Univ. (United States); Mustafa M. Shihab, Peng Zhou, Xuan Hu, The Univ. of Texas at Dallas (United States); Jayasimha Atulasimha, Virginia Commonwealth Univ. (United States); Yiorgos Makris, Joseph S. Friedman, The Univ. of Texas at Dallas (United States)
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Prevention of integrated circuit counterfeiting through logic locking faces the fundamental challenge of securing an obfuscation key against physical and algorithmic threats. Previous work has focused on strengthening the logic encryption to protect the key against algorithmic attacks but failed to provide adequate physical security. In this work, we propose a logic locking scheme that leverages the non-volatility of the nanomagnet logic (NML) family to achieve both physical and algorithmic security. Polymorphic NML minority gates protect the obfuscation key against algorithmic attacks, while a strain-inducing shield surrounding the nanomagnets provides physical security via a self-destruction mechanism, securing against invasive attacks. We experimentally demonstrate that shielded magnetic domains are indistinguishable, securing against imaging attacks. As NML suffers from low speeds, we propose a hybrid CMOS logic scheme with embedded obfuscated NML “islands”. The NML secures the functionality of sensitive logic while CMOS drives the timing-critical paths.
12205-28
Author(s): Alexander J. Edwards, The Univ. of Texas at Dallas (United States); Dhritiman Bhattacharya, Virginia Commonwealth Univ. (United States); Peng Zhou, The Univ. of Texas at Dallas (United States); Nathan R. McDonald, Lisa Loomis, Clare D. Thiem, Air Force Research Lab. (United States); Jayasimha Atulasimha, Virginia Commonwealth Univ. (United States); Joseph S. Friedman, The Univ. of Texas at Dallas (United States)
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We present initial experimental results and simulate a nanomagnet reservoir computer (NMRC) solving tasks requiring high memory content, with an area-energy-delay product ten-million times lower than CMOS systems. We manufactured a small nanomagnet reservoir demonstrating a frustrated state. We evaluated the performance on two novel tasks. Our results indicate the reservoir’s short-term memory capabilities and ability to integrate information from multiple concurrent inputs. In the end, our system saw a reduction in area by a factor of 50,000, in energy by a factor of 60, and in period by a factor of four as compared with an equivalent CMOS reservoir.
12205-29
Author(s): Peng Zhou, Alexander J. Edwards, The Univ. of Texas at Dallas (United States); Fred B. Mancoff, Dimitri Houssameddine, Sanjeev Aggarwal, Everspin Technologies, Inc. (United States); Joseph S. Friedman, The Univ. of Texas at Dallas (United States)
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We present the first experimental demonstration of a neuromorphic network with magnetic tunnel junction (MTJ) synapses, which performs image recognition via vector-matrix multiplication. We also simulate a large MTJ network performing MNIST handwritten digit recognition, demonstrating that MTJ crossbars can match memristor accuracy while providing increased precision, stability, and endurance.
12205-30
Author(s): Chloé Chopin, Simon de Wergifosse, Flavio Abreu Araujo, Univ. Catholique de Louvain (Belgium)
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A semi-analytical method (data-driven model) is used to predict the dynamics of a Spin-Torque Vortex Oscillator (STVO). This model relies on an improved analytical model based on the Thiele equation approach and micromagnetic simulations. The improved analytical model shows that the Ampère-Oersted field cannot be neglected and it describes quantitatively the STVO dynamics only in the resonant regime when the data-driven model allows to describe it in the steady-state oscillating regime as well. In addition, the model is 2.1 million time faster than simulations. It can be used to simulate the spin-diode effect and functionalize the STVOs for neuromorphic applications.
12205-81
Author(s): Damien Querlioz, Univ. Paris-Saclay (France)
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This work introduces a methodology for modeling spintronic systems based on a deep learning approach. We show that using a limited amount of micromagnetic simulations or experimental data, we can train a specific type of neural network known as “Neural Ordinary Differential Equations” to predict the behavior of a spintronic system in new situations. On the simulation of a skyrmion-based system, our technique gives equivalent results to micromagnetic simulations but 200 times faster. We also show that based on five milliseconds of experimental data, our method predicted the results of weeks of measurements of spin-torque nanooscillators.
Session 8: Van der Waals Spintronics
12205-31
Author(s): Felix Casanova, CIC nanoGUNE (Spain), IKERBASQUE, Basque Foundation for Science (Spain)
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Transition metal dichalcogenides (TMD) can be used to enhance the spin-orbit coupling of graphene, leading to new spin transport channels with unprecedented spin textures. We have optimized bilayer graphene/WSe2 van der Waals heterostructures to achieve magnetic-field-free spin precession. Remarkably, the sign of the precessing spin polarization can be tuned electrically by backgate voltage and drift current, being the first realization of a spin field-effect transistor at room temperature in a diffusive system. The spin-orbit proximity in graphene/TMD van der Waals heterostructures also leads to spin Hall effect (SHE), first observed by our group using MoS2 as the TMD. The combination of long-distance spin transport and SHE in the same material gives rise to an unprecedented figure of merit (product of spin Hall angle and spin diffusion length) of 40 nm in graphene proximitized with WSe2, which is also gate tunable.
12205-32
Author(s): John Cenker, Univ. of Washington (United States)
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Mechanical deformation of a crystal can have a profound effect on its physical properties. Here we report the strain tuning of the magnetic properties of the A-type layered antiferromagnetic semiconductor CrSBr achieved by designing a strain device that can apply continuous, in situ uniaxial tensile strain to two-dimensional materials, reaching several percent at cryogenic temperatures. Using this apparatus, we realize a reversible strain-induced antiferromagnetic-to-ferromagnetic phase transition at zero magnetic field and strain control of the out-of-plane spin-canting process. Our work creates new opportunities for harnessing the strain control of magnetism and other electronic states in low-dimensional materials and heterostructures.
12205-33
Author(s): Xintong Li, Jean Anne Incorvia, Zhida Liu, The Univ. of Texas at Austin (United States); Yihan Liu, Univ. of Pittsburgh (United States); Suyogya Karki, Xiaoqin Li, Deji Akinwande, The Univ. of Texas at Austin (United States)
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Couple spin and valley Hall effect (SVHE) in 2-dimensional transition metal dichalcogenides (TMD) monolayers is an efficient way of converting charge current to spin and valley current, making the electrical generation of spin and valley polarization possible for practical spintronic and valleytronic applications. Here we conduct spatial Kerr rotation measurements on monolayer tungsten diselenide (WSe2) transistors and study the electrical control and temperature dependence of SVHE. We find clear evidence of the spin and valley accumulation at the edges and show that it can be electrically modulated by the gate and drain bias and that it persists at elevated temperatures.
Session 9: Spin-Hall Effect and Spin-Orbit Torque
12205-34
Author(s): Yunqiu Kelly Luo, Cornell Univ. (United States)
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We develop an ultrasensitive magneto-optic method to quantify spin-orbit torques (SOT) based on a modified Sagnac magneto-optic Kerr effect (MOKE) interferometry (~ 5μRad/√Hz). The high sensitivity of Sagnac interferometry permits for the first time optical quantification of spin-orbit torque from small-angle magnetic tilting of samples with perpendicular magnetic anisotropy (PMA). We find significant disagreement between Sagnac measurements and simultaneously-performed harmonic Hall (HH) measurements of spin-orbit torque on Pt/Co/MgO and Pd/Co/MgO samples with PMA. This very surprising result demonstrates a flaw in the most-popular method for measuring spin-orbit torques in PMA samples, and represents an unsolved puzzle in understanding the planar Hall effect in magnetic thin films.
12205-35
Author(s): Anastasiia Moskaltsova, Timo Kuschel, Univ. Bielefeld (Germany)
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We investigated the magnetic proximity effect (MPE) as well as the unidirectional spin Hall magnetoresistance (USMR) and spin-orbit torques (SOTs) in heavy metal/Co/heavy metal trilayer systems compared to Pt/Co and Ta/Co bilayers. By using x-ray resonant magnetic reflectivity, we obtained magnetic depth profiles of the structural, optical and magnetic parameters, and studied the impact of the MPE in Pt on the total magnetic moment of the systems. A detailed analysis of harmonic longitudinal and Hall voltage measurements revealed enhanced SOTs and USMR in the trilayers that include a second heavy metal with the opposite sign of the spin Hall angle.
12205-36
Author(s): Jean-Eric Wegrowe, Ecole Polytechnique (France)
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The stationary state of the spin-Hall bar is studied in the framework of a variational approach that includes non-equilibrium screening effects at the lateral edges. The minimization of the power dissipated in the system is performed with taking into account the spin-flip relaxation and the global constrains due to the electric generator and global charge conservation. The calculation is performed within both the approximations of negligible spin-flip scattering and strong spin-flip scattering. In both cases, simple expressions the longitudinal and the transverse pure spin-currents are derived analytically. In the first case, the spin-accumulation is linear across the Spin-Hall bar, symmetric from one edge to other, and the transverse spin-current vanishes. With strong spin-flip scattering, a transverse pure spin-current flows across the sample together with with longitudinal pure spin-current. Surprisingly, due to the small values of the screening Debye length, the effect of the spin-flip scattering seems not to change significantly the profile and the amplitude of the spin-accumulation. A quantitative analysis predicts a spin accumulation of the order of $1\%$ of the density of carriers for an applied electric field of $5 mV/\m m^2$ at $30K$, with a spin-Hall angle of $\theta_{SH} = 10^{-4}$.
Session 10: Coherence and Ballistic Transport
12205-38
Author(s): Michael E. Flatté, The Univ. of Iowa (United States)
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I will introduce the fundamental requirements for practically linking quantum objects into large-scale coherent quantum systems as well as the advantages of coherent magnonics for next-generation quantum coherent systems (i.e., spin-entangling quantum gates). Other critical challenges for quantum information science then will motivate the development of coherent magnonics for quantum transduction from “stationary” spin systems to “flying” magnons and for quantum memory. Finally, the advantages of all-magnon quantum information technologies that rely on manipulating and encoding quantum information in superpositions of fixed magnon number states will highlight the potential of new magnetic materials, devices, and systems.
12205-39
Author(s): Valentin Desbuis, Daniel Lacour, Institut Jean Lamour (France); Coriolan Tiusan, Ctr. of Supraconductivity, Spintronics and Surface Science (Romania); Christopher Vautrin, Yuan Lu, Institut Jean Lamour (France); Wolfgang Weber, Institut de Physique et de Chimie des Matériaux de Strasbourg (France); Michel Hehn, Institut Jean Lamour (France)
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Electronic spin precession and filtering is measured in the molecular field of a Co50Al50 thin film. Designed to have the Curie temperature less than 150K, the variation of the Co50Al50 molecular field results in an electronic spin precession angle that oscillates with temperature. This behavior could be observed for injection energies between 0.8 and 1.1 eV. Obtained values are of the same order of magnitude as recently measured CoFeB devices over the same energy range. The results are explained on the basis of an exchange field varying with temperature, the layer roughness and Al diffusion towards the tunnel barrier
12205-40
Author(s): Herbert F. Fotso, Univ. at Albany, The State Univ. of New York (United States), Univ. at Buffalo, The State Univ. of New York (United States); Kathy-Anne Soderberg, David Hucul, Air Force Research Lab. - Rome (United States)
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We demonstrate the use of external field protocols to control optical properties of quantum spins for optimized photon-mediated operations in quantum information processing. Specifically, we study two-photon interference operations between spectrally different quantum emitters. We show that, well beyond their idealized versions, appropriate external field protocols can suppress spectral diffusion, mitigate inhomogeneous broadening and restore photon indistinguishability between spectrally different quantum emitters. These protocols can play an important role in enabling more efficient light-matter interfaces that are essential for scalable quantum information processing platforms.
12205-41
Author(s): Valentin Desbuis, Daniel Lacour, Institut Jean Lamour (France); Coriolan Tiusan, Ctr. of Superconductivity, Spintronics and Surface Science, Univ. Tehnica din Cluj Napoca (Romania); Yuan Lu, Christopher Vautrin, Institut Jean Lamour (France); Wolfgang Weber, Institut de Physique et de Chimie des Matériaux de Strasbourg (France); Michel Hehn, Institut Jean Lamour (France)
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Ballistic hot electrons, whose energy is lower than 2.5 eV, are extracted from a magnetic tunnel junction and injected into a metallic base. After passing through the base, the electrons are energy filtered by a Schottky barrier. The use of a low height Si/Cu Schottky barrier allows to disentangle the different contributions to the scattering. The hot electrons transport is interpreted as being mainly influenced by inelastic diffusion. A transport model reproduces our measurements and explains them as resulting directly from a diffusion process related to the d-band of the ferromagnetic material involved.
Session 11: Spin Lasers
12205-42
Author(s): Niels Heermeier, Tobias Heuser, Jan Große, Technische Univ. Berlin (Germany); Natalie Jung, Ruhr-Univ. Bochum (Germany); Arsenty Kaganskiy, Technische Univ. Berlin (Germany); Markus Lindemann, Nils C. Gerhardt, Martin R. Hofmann, Ruhr-Univ. Bochum (Germany); Stephan Reitzenstein, Technische Univ. Berlin (Germany)
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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-oscillation frequency can be engineered via the pillar cross-section. The microlasers show very pronounced spin-lasing effects with polarization oscillation frequencies up to 15 GHz.
12205-43
Author(s): Nobuhide Yokota, Tohoku Univ. (Japan); Kazuhiro Ikeda, National Institute of Advanced Industrial Science and Technology (Japan); Hiroshi Yasaka, Tohoku Univ. (Japan)
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We report on injection-locked spin-VCSELs for application to coherent optical communication systems. Simulated results based on spin-flip rate equations indicate that a modulation sideband of an injection-locked spin-VCSEL can be used as a frequency-shifted local oscillator for optical signal detection in coherent optical communication systems. Optical modulation of electron spin polarization in an injection-locked InAlGaAs VCSEL experimentally confirms that spin polarization modulation responses of the VCSEL depends on injection power conditions for the injection locking, and reasonably agree with those of simulations. These results suggest a novel application of spin-VCSELs, namely, a frequency-shifted local oscillator can be achieved by directly modulating an injection-locked spin-VCSEL without using external modulators.
12205-44
Author(s): Nianqiang Li, Yu Huang, Pei Zhou, Soochow Univ. (China)
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We have numerically investigated the high-frequency dynamic properties of optically pumped spin-VCSELs. The effect of some key parameters on the polarization modulation and periodic oscillation was illustrated clearly. More interestingly, in the CW regions, we have shown how to reveal two resonance peaks; one was located at the RO frequency and the other was at the value of the frequency splitting between the two orthogonally polarized VCSEL modes. In the periodic regions, we have demonstrated a photonic microwave generation scheme based on the period one oscillation state of a solitary spin-VCSEL. Our results open up new research fields into spin-VCSELs.
12205-45
Author(s): Francisco Freire Fernandez, Northwestern Univ. (United States); Javier Cuerda, Aalto Univ. (Finland); Konstantinos Daskalakis, Univ. of Turku (Finland); Sreekanth Perumbilavil, Jani P. Martikainen, Kristian Arjas, Päivi Törmä, Sebastiaan van Dijken, Aalto Univ. (Finland)
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The nanoscale mode volumes of surface plasmon polaritons have enabled plasmonic lasers and condensates with ultrafast operation. Most plasmonic lasers are based on noble metals, rendering the optical mode structure inert to external fields. Here we demonstrate active magnetic-field control over lasing in a periodic array of Co/Pt multilayer nanodots immersed in an IR-140 dye solution. We exploit the magnetic nature of the nanoparticles combined with mode tailoring to control the lasing action. Under circularly polarized excitation, angle-resolved photoluminescence measurements reveal a transition between the lasing action and non-lasing emission as the nanodot magnetization is reversed. Our results introduce magnetization as a means of externally controlling plasmonic nanolasers, complementary to modulation by excitation, gain medium, or substrate. Further, the results show how the effects of magnetization on light that are inherently weak can be observed in the lasing regime, inspiring studies of topological photonics
12205-46
Author(s): Mariusz Drong, VŠB-Technical Univ. of Ostrava (Czech Republic), Ecole Polytechnique, Institut Polytechnique de Paris (France); Henri Jaffrès, Unité Mixte de Physique CNRS/Thales (France); Tibor Fördös, Kamil Postava, VŠB-Technical Univ. of Ostrava (Czech Republic); Henri-Jean M. Drouhin, Ecole Polytechnique, Institut Polytechnique de Paris (France)
Session 12: Spin Photonics
12205-47
Author(s): Henri-Jean M. Drouhin, Lab. des Solides Irradiés, Ecole Polytechnique (France), CEA-DRF-IRAMIS (France), CNRS (France); Viatcheslav I. Safarov, Lab. des Solides Irradiés, Ecole Polytechnique (France), CEA-DRF-IRAMIS (France), CNRS (France); Igor V. Rozhansky, Ioffe Institute (Russian Federation); Henri Jaffrès, Unité Mixte de Physique CNRS/Thales, Univ. Paris-Saclay (France); Yuan Lu, Institut Jean Lamour, Univ. de Lorraine, CNRS (France)
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Spin optoelectronics has the ability to interconvert photon spins to electrical charges and may revolutionize information processing. Circularly-polarized photon sources rely on spin lasers whereas reciprocal devices are solid-state helicity detectors, the fabrication of which has remained a challenge for decades. Experimental results obtained on a ferromagnetic CoFeB/MgO/III-V semiconductor tunnel diode will be presented. We show that the helicity-dependent photocurrent is mostly determined by a dynamical factor resulting from the competition between carrier recombination in the metal and in the semiconductor. This constitutes a radical shift in the description of these emerging spin devices.
12205-48
Author(s): Yuan Lu, Institut Jean Lamour (France); Pierre Renucci, Univ. de Toulouse (France), Institut National des Sciences Appliquées de Lyon (France), Lab. de Physique et Chimie des Nano-objets (France); Henri Jaffrès, Unité Mixte de Physique CNRS/Thales (France); Xavier Marie, Univ. de Toulouse (France), Institut National des Sciences Appliquées de Lyon (France), Lab. de Physique et Chimie des Nano-objets (France); Jean-Marie George, Unité Mixte de Physique CNRS/Thales (France)
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Spin optoelectronic devices (spin light-emitting diode, spin laser and spin photodiode), which can convert the carrier spin polarization with the photon circular polarization, have gained intensive interest in the last decade. The potential applications of spin optoelectronic device can be used for optical communication, 3D display, biomedical analyses, etc. However, the obstacles for developing these applications are relied on the room temperature operation and without applying the magnetic field. According to the optical selection rule, for surface emitting and detecting geometry, the conventional spin injector with in-plane magnetization requires a strong external magnetic field in the range of a few Tesla, which is impossible for the practical application. Since 2014, we have developed the spin injector with perpendicular magnetic anisotropy (PMA) consisting of an ultrathin CoFeB (1.2 nm)/MgO (2.5 nm) on GaAs based quantum well (QW) [1] and quantum dot (QD) LED [2]. In this talk, I will give a presentation on our progress on developing PMA spin injector with better thermal stability [3], the evidence of polarization of nuclei spin by electron pin [2], the understanding of spin relaxation mechanism in spin LED [4] and the developing of spin photodiode with PMA spin detector [5]. References: [1] S. H. Liang, T. T. Zhang, P. Barate, J. Frougier, M. Vidal, P. Renucci, B. Xu, H. Jaffrès, J.-M. George, X. Devaux, M. Hehn, X. Marie, S. Mangin, H. X. Yang, A. Hallal, M. Chshiev, T. Amand, H. F. Liu, D. P. Liu, X. F. Han, Z. G. Wang, and Y. Lu, “Large and robust electrical spin injection into GaAs at zero magnetic field using an ultrathin CoFeB/MgO injector”, Physical Review B, 90, 085310 (2014). [2] F. Cadiz, A. Djeffal, D. Lagarde, A. Balocchi, B. S. Tao, B. Xu, S.H. Liang, M. Stoffel, X. Deveaux, H. Jaffres, J.M. George, M. Hehn, S. Mangin, H. Carrere, X. Marie, T. Amand, X. F. Han, Z. G. Wang, B. Urbaszek, Y. Lu, and P. Renucci, “Electrical initialization of electron and nuclear spins in a single quantum dot at zero magnetic field”, Nano Letters 18, 2381 (2018). [3] Bingshan Tao, Philippe Barate, Xavier Devaux, Pierre Renucci, Julien Frougier, Abdelhak Djeffal, Shiheng Liang, Bo Xu, Michel Hehn, Henri Jaffrès, Jean-Marie George, Xavier Marie, Stéphane Mangin, Xiufeng Han, Zhanguo Wang and Yuan Lu, “Atomic-Scale Understanding of High Thermal Stability of Mo/CoFeB/MgO Spin Injector for Spin-Injection in Remanence”, Nanoscale 10, 10213-10220 (2018). [4] Alaa E. Giba, Xue Gao, Mathieu Stoffel, Xavier Devaux, Bo Xu, Xavier Marie, Pierre Renucci, Henri Jaffrès, Jean-Marie George, Guangwei Cong, Zhanguo Wang, Hervé Rinnert and Yuan Lu, “Spin Injection and Relaxation in p-Doped (In,Ga)As/GaAs Quantum-Dot Spin Light-Emitting Diode at Zero Magnetic Field”, Physical Review Applied 14, 034017 (2020). [5] F. Cadiz, D. Lagarde, B. Tao, J. Frougier, B. Xu, X. Devaux, S. Migot, Z. G. Wang, X. F. Han, J.-M. George, H. Carrere, A. Balocchi, T. Amand, X. Marie, B. Urbaszek, H. Jaffrès, Y. Lu and P. Renucci, “Electrical detection of light helicity using a quantum-dot-based hybrid device at zero magnetic field”, Physical Review Materials 4, 124603 (2020).
12205-49
Author(s): Yuqing Huang, Linköping Univ. (Sweden); Ville Polojärvi, Tampere Univ. (Finland); Satoshi Hiura, Hokkaido Univ. (Japan); Arto Aho, Riku Isoaho, Teemu Hakkarainen, Mircea Guina, Tampere Univ. (Finland); Akihiro Murayama, Hokkaido Univ. (Japan); Irina A. Bouianova, Weimin M. Chen, Linköping Univ. (Sweden)
Session 13: Superconducting and Voltage-Controlled Spintronics
12205-50
Author(s): Changjiang Liu, Univ. at Buffalo, The State Univ. of New York (United States); Yongming Luo, Hangzhou Dianzi Univ. (China); Deshun Hong, Chongqing Univ. (China); Shulei Zhang, Case Western Reserve Univ. (United States); Hilal Saglam, Princeton Univ. (United States); Yi Li, Yulin Lin, Brandon Fisher, John Pearson, J. Samuel Jiang, Hua Zhou, Jianguo Wen, Argonne National Lab. (United States); Axel Hoffmann, Univ. of Illinois (United States); Anand Bhattacharya, Argonne National Lab. (United States)
12205-51
Author(s): Matthias Althammer, Walter Schottky Institut, Bayerische Akademie der Wissenschaften (Germany)
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Proximity effects at superconductor(SC)/ferromagnet(FM) interfaces provide novel functionality in the field of superconducting spintronics. We investigate the spin current transport in SC/Permalloy (Py) heterostructures with a Pt spin sink layer. To this end, we excite ferromagnetic resonance in the Py-layer via a coplanar waveguide (CPW) at different microwave frequencies. A phase sensitive detection of the microwave transmission signal is used to quantitatively extract the inductive coupling strength between sample and CPW as a function of temperature. This approach enables the analysis of ac charge currents excited by the magnetization precession in SC/FM hybrids, like inverse spin-orbit torque induced charge currents.
12205-52
Author(s): Matías Grassi, Institut de Physique et de Chimie des Matériaux de Strasbourg (France); Moritz Geilen, Technische Univ. Kaiserslautern (Germany); Kosseila Ait Oukaci, Institut Jean Lamour (France); Yves Henry, Institut de Physique et de Chimie des Matériaux de Strasbourg (France); Daniel Lacour, Institut Jean Lamour (France); Daniel Stoeffler, Institut de Physique et de Chimie des Matériaux de Strasbourg (France); Michel Hehn, Institut Jean Lamour (France); Philipp Pirro, Technische Univ. Kaiserslautern (Germany); Matthieu Bailleul, Institut de Physique et de Chimie des Matériaux de Strasbourg (France)
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Spontaneous symmetry breaking is ubiquitous in physics. Its spectroscopic signature consists in the softening of a mode upon approaching the transition from the high symmetry side, and its subsequent splitting into a zero-frequency ‘Goldstone’ mode and a non-zero-frequency ‘Higgs’ mode. In this work, we study the weak stripe domains, a periodic magnetic modulation occurring in ferromagnetic films with perpendicular-to-plane magnetic anisotropy, and observe its Goldstone and Higgs spin-wave modes at room temperature using microwave and optical techniques. This simple system constitutes a convenient platform for exploring the dynamics of symmetry breaking, and the interplay between spin waves and static magnetic textures.
12205-54
Author(s): Jason Robinson, Univ. of Cambridge (United Kingdom)
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This talk will review my group’s recent progress in generating pure spin supercurrents in superconducting proximity structures and the optimization of magnetic proximity effects in nearly a nm-thick s-wave. In the first part of the talk I will demonstrate spin-triplet pair generation via spin-orbit coupling and magnetic exchange fields and in the second part I will demonstrate infinite magnetoresistance in superconducting Nb sandwiched between insulating ferromagnetic layers. The results are key the development of superconducting spintronics.
Session 14: Voltage-Controlled Spintronics
12205-55
Author(s): Pedram Khalili, Northwestern Univ. (United States)
12205-56
Author(s): Jayasimha Atulasimha, Virginia Commonwealth Univ. (United States)
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Electrical field control of magnetization in nanoscale magnets has the potential to be extremely energy efficient. We will discuss voltage-induced strain and acoustic wave switching of the magnetization as well as direct voltage control of magnetic anisotropy (VCMA) to control magnetic skyrmion states in nanomagnets with confined geometry. We will then discuss various voltage-controlled nanoscale magnetic device proposals towards implementation of energy efficient, memory, deep neural networks whose synaptic weights can be reprogrammed online and reservoir computing devices that are amenable to online training. This could be a key enabling technology for edge computing in IOT devices.
12205-57
Author(s): Christian C. Rinaldi, Politecnico di Milano (Italy)
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In the quest for ultra-low power electronic devices beyond the CMOS platform, ferroelectric Rashba semiconductors offer intriguing possibilities. After an overview of the main findings in this context, I will show that the ferroelectric polarization of epitaxial thin films of GeTe can be reliably switched by electrical gating and used to control spin-to-charge conversion by spin Hall effect. Ferroelectricity allows for efficient switching and stable state retention, while spin currents provides an effective read-out of the memory state. Doping, allowing and dimensionality can be used to tailor the properties of these compounds towards logic-in-memory devices with monolithic integrability with silicon.
12205-58
Author(s): Aymen Fassatoui, Cristina Balan, Jose Pena-garcia, Institut NÉEL (France); Hélène Béa, Spintec, CNRS (France), CEA (France); Laurent Ranno, Jan Vogel, Stefania Pizzini, Institut NÉEL (France)
12205-59
Author(s): Aurélie Kandazoglou, Cécile Grezes, Maxen Cosset-Chéneau, Spintec, CNRS (France), CEA (France); Luis Moreno Vincente-Arche, Unité Mixte de Physique CNRS/Thales (France); Paolo Sgarro, Spintec, CNRS (France), CEA (France); Paul Noël, ETH Zurich (Switzerland); Stéphane Auffret, Kévin Garello, Spintec, CNRS (France), CEA (France); Manuel Bibes, Unité Mixte de Physique CNRS/Thales (France); Laurent Vila, Jean-Philippe Attané, Spintec, CNRS (France), CEA (France)
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This work reports remanent electric-control of spin-orbit torques (SOT) in a perpendicular ferromagnet-SrTiO3 system. Non-volatile electric-control of the sheet resistance is achieved with 1150% contrast, and two remanent resistivity states. A remanent electric-control of the SOT efficiency is demonstrated using second harmonic Hall methods, with sign inversion of the anti-damping-like effective field. These results are consistent with a combination of both intrinsic modulation of the SOT efficiency and extrinsic modulation due to the non-volatile electric-control of the current injection in the 2DEG. The non-volatile control of the SOT effective field is evidenced by reproducible inversion of the SOTs after voltage pulses initialization, opening the way to reconfigurable SOT memories and logic-gate architectures.
Session 15: Magneto Optics and Imaging
12205-60
Author(s): Peter Wahl, Univ. of St. Andrews (United Kingdom)
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STM performed with a magnetic tip allows for spin-polarized imaging of magnetism at the atomic scale, providing direct real-space insights into complex magnetic orders. in my talk, I will show how an STM can also be used to probe magnetic exchange interactions, using Helium in the tunneling junction. I will present a study of the influence of Helium probe particles on spin-polarized imaging in a low temperature scanning tunneling microscope. From tunneling spectra acquired at different tip-sample distances we can map out the binding energy of the Helium atom in the tunneling junction. We find that imaging with Helium trapped in the tunneling junction makes the STM sensitive to the magnetic exchange interaction between the tip and the sample. By changing the tip-sample separation the intensity of the imaged magnetic order can be both enhanced and suppressed and the overall spin-polarization of the tunneling current can be tuned by varying the bias voltage. This effectively enables voltage-control of the spin-polarization of the tunneling current across the junction.
12205-61
Author(s): Giti A. Khodaparast, Nicholas W. G. Smith, Shuang Wu, Satoru Emori, Brenden A. Magill, Rathsara H. Mudiyanselage, Virginia Polytechnic Institute and State Univ. (United States); Jade Holleman, Stephen McGill, National High Magnetic Field Lab. (United States); Min Gyu Kang, Priya Shashank, The Pennsylvania State Univ. (United States); Christopher Stanton, Univ. of Florida (United States)
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In this work, we focused on probing optical properties of BaTiO3-BiFeO3 (BTO-BFO) films and nano-rod arrays by employing transient reflectivity and time-resolved magneto-optical Kerr effect. We performed these measurements via pump/probe optical techniques in high external magnetic fields (up to 10 T). The pump laser was fixed at 400 nm (1 KHz repetition rate), which allowed us to generate Coherent Longitudinal Acoustic Phonons (CLAPs) within the samples, and we used 800 nm pulses as the probe. We observed strong sensitivity of CLAPs to the external magnetic fields, and we also observed coherent oscillations with frequencies, close to the predicted magnon frequencies. The ability to generate strain waves via ultrafast optics offers the intriguing possibility of dynamically manipulating the strain in a given sample with ultrashort optical pulses which opens the possibility of creating a new class of devices, on the basis of our lesser explored multiferroics, where the strain can be manipulated in time to control the properties and operation of a device. Furthermore, in designing magneto-electric devices, magnetic materials systems with low Gilbert damping are desirable. From broadband ferromagnetic resonance spectroscopy, we estimate low effective Gilbert damping parameters on the order of 7x10^-3, albeit with rather large inhomogeneous linewidth broadening of >10 mT, in films of BTO-BFO directly grown on SiO2 (1 µm)/Si. This material is based upon work supported by the Air Force Office of Scientific Research under award number FA9550-17-1-0341, and DURIP funding (FA9550-16-1-0358). A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by the National Science Foundation Cooperative Agreement No. DMR-1644779 and the State of Florida.
12205-62
Author(s): Peter Fischer, Lawrence Berkeley National Lab. (United States)
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This talk presents recent achievements with advanced magnetic soft X-ray spectro-microscopies to investigate the static properties and dynamic behavior of novel topological spin textures, such as skyrmions and Hopfions which is critical towards the use of novel magnetic materials in fast, small and low-power spintronics technologies. Advanced characterization tools providing magnetic sensitivity to spin textures, disentangling the role of individual components in heterogeneous material at high spatial resolution, at buried interfaces, in all three dimensions, and at high temporal resolution to capture the spin dynamics across scales, are required to address those questions, and are therefore of large scientific interest.
12205-63
Author(s): Daniel Lacour, Kosseila Ait Oukaci, Institut Jean Lamour (France); Daniel Stoeffler, Institut de Physique et de Chimie des Matériaux de Strasbourg (France); B. Sarpi, Synchrotron SOLEIL (France); F. Montaigne, Institut Jean Lamour (France); R. Belkhou, Synchrotron SOLEIL (France); M. Hehn, Institut Jean Lamour (France)
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High-resolution scanning transmission X-ray microscopy (STXM) can provide quantitative access to the tilt angles of the local magnetization with respect to the surface. We use this state-of-the-art microscopy technique to probe the magnetic texture of the weak stripes texture hosted by a 180 nm thick Co40Fe40B20 layer. We report a comprehensive set of measurements of the weak stripes texture tilt angle, as well as a method that uses only a single direction x-ray beam to extract the angle. This method also extracts the spatial profile with 30 nm resolution and measures the tilt angle as a function of the applied field. Combining these informations, the macroscopic loop of magnetization as a function of applied field on a complex spin texture can be reconstructed in an unprecedented way and shows without doubt that flux closure domains exist. Beyond the characterization of the weak stripe angle, this quantitative magnetic X-ray microscopy technique can be used to study the local textures present in all materials exhibiting some circular magnetic X-ray dichroism.
12205-64
Author(s): Pauli Kehayias, Sandia National Labs. (United States)
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The quantum diamond microscope (QDM) is a recently-developed technology used for magnetic imaging with high spatial resolution. The QDM offers micron-scale resolution over a few-mm field of view, high-reliability operation in ambient conditions, and high signal-to-noise readout of nano- and micro-scale magnetic sources, which have enabled scientific results that were previously impractical or impossible. I will present recent results applying QDM techniques to magnetically interrogating behavior and phenomena in commercial electronic devices, with applications to nanomagnetism and electrical engineering.
Session 16: Nanomagnetism and Magnonics
12205-65
Author(s): Christopher Barker, Univ. of Leeds (United Kingdom); Simone Finizio, Paul Scherrer Institut (Switzerland); Craig Barton, National Physical Lab. (United Kingdom); Eloi Haltz, Univ. of Leeds (United Kingdom); Sophie Morley, Lawrence Berkeley National Lab. (United States); Francesco Maccherozzi, Brice Sarpi, Diamond Light Source Ltd. (United Kingdom); Sina Mayr, Paul Scherrer Institut (Switzerland), ETH Zurich (Switzerland); Thomas Moore, Gavin Burnell, Univ. of Leeds (United Kingdom); Jörg Raabe, Paul Scherrer Institut (Switzerland); Olga Kazakova, National Physical Lab. (United Kingdom); Christopher H. Marrows, Univ. of Leeds (United Kingdom)
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We report studies of spin textures including domain walls and skyrmions in synthetic antiferromagnetic multilayers. We have observed: phase coexistence of uniform antiferromagnetic regions with textured ferromagnetic regions during magnetisation; current-driven domain wall motion at lower current densities than in comparable ferromagnetic multilayers; and current-driven nucleation of a synthetic antiferromagnetic skyrmion.
12205-66
Ferrimagnetic spintronics (Invited Paper)
Author(s): Kyung-Jin Lee, KAIST (Korea, Republic of)
12205-68
Author(s): Kyusup Lee, Hyunsoo Yang, National Univ. of Singapore (Singapore)
Session 17: Orbital Torque and Spin-Seebeck Effect
12205-69
Author(s): Dongwook Go, Forschungszentrum Jülich GmbH (Germany), Jülich Aachen Research Alliance (Germany); Young-Gwan Choi, Sungkyunkwan Univ. (Korea, Republic of); Daegeun Jo, Pohang Univ. of Science and Technology (Korea, Republic of); Kyung-Hun Ko, Sungkyunkwan Univ. (Korea, Republic of); Kyung-Han Kim, Pohang Univ. of Science and Technology (Korea, Republic of); Hee Gyum Park, Korea Institute of Science and Technology (Korea, Republic of); Changyoung Kim, Seoul National Univ. (Korea, Republic of); Byoung-Chul Min, Korea Institute of Science and Technology (Korea, Republic of); Gyung-Min Choi, Sungkyunkwan Univ. (Korea, Republic of); Hyun-Woo Lee, Pohang Univ. of Science and Technology (Korea, Republic of)
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Recent theories have predicted that unlike the spin Hall effect, the orbital Hall effect can be gigantic even in light metals because it does not require spin-orbit interaction [1]. This opens a novel route toward electric control of magnetic moments in spintronic devices by harnessing the angular momentum carried by orbital current [2]. As the choice of materials is not restricted to heavy elements, utilizing the orbital current offers great flexibility in choosing environment-friendly materials [3]. In recent years, so-called the orbital torque mechanism has been found in various magnetic heterostructures, demonstrating its potential for highly efficient spintronic devices [4-7]. So far, however, direct experimental evidence of the orbital current has still been missing. In this talk, we present a magneto-optical measurement of the orbital accumulation induced by the orbital Hall effect in a light metal Ti [8]. The orbital accumulation at the surface of Ti leads to ~ 50 nrad of Kerr rotation of a polarized light for current density ~107 A/cm2, which is of the same order of magnitude for the Kerr rotation induced by the spin Hall effect in Pt [9]. Our analysis based on semi-realistic calculations shows that this cannot be explained by the spin Hall effect, which is far too small in Ti, and the estimation of the Kerr angle caused by the spin accumulation is two orders of magnitude smaller than what we observe in experiment. Moreover, variations of the sign and magnitude of the Kerr angle agree with the theoretical model based on the orbital Hall effect while they significantly deviate from the model based on the spin Hall effect. As another evidence, we also measure the orbital torque in Ti/Co heterostructures. We find gigantic field-like component, which amounts to the orbital Hall angle of 0.3. Our experimental results, which are corroborated by theoretical analyses, provide a direct and strong evidence of the orbital Hall effect and serve as a solid ground for future directions of orbitronics research [10]. References: [1] D. Go et al., Phys. Rev. Lett. 121, 086602 (2018). [2] D. Go and H.-W. Lee, Phys. Rev. Res. 2, 013177 (2020). [3] D. Jo, D. Go, and H.-W. Lee, Phys. Rev. B 98, 214405 (2018). [4] S. Ding et al., Physical Review Letters 125, 177201 (2020). [5] J. Kim et al., Phys. Rev. B 103, L020407 (2021). [6] S. Lee et al., Commun. Phys. 4,234 (2021). [7] D. Lee et al., Nat. Commun. 12, 6710 (2021). [9] Y.-G. Choi et al., arXiv:2109.14847. [9] C. Stamm et al., Phys. Rev. Lett. 119, 087203 (2017). [10] D. Go et al., Europhys. Lett. 135, 37001 (2021).
12205-70
Author(s): OukJae Lee, Korea Institute of Science and Technology (Korea, Republic of); Kyung-Jin Lee, KAIST (Korea, Republic of); Hyun-Woo Lee, Pohang Univ. of Science and Technology (Korea, Republic of); Dongjoon Lee, Korea Institute of Science and Technology (Korea, Republic of); Dongwook Go, Peter Grünberg Institut (IPG), Forschungszentrum Jülich GmbH (Germany), Institute for Advanced Simulation (IAS), Forschungszentrum Jülich GmbH (Germany); Hyeon-Jong Park, KAIST (Korea, Republic of)
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The orbital Hall effect describes an electric-field-induced generation of the orbital current flowing in a perpendicular direction to the field, analogous to the spin Hall effect [1]. As the orbital current carries the angular momentum as the spin current does, injection of the orbital current into a ferromagnet can result in spin-torque on the magnetization, which provides a way to detect the orbital Hall effect [2]. With this motivation, we examine the current-induced spin-orbit torques in various ferromagnet/heavy metal bilayers [3]. Analysis of the spin-torque reveals the presence of the contribution from the orbital Hall effect in the heavy metal. In particular, we find that the net torque in Ni/Ta bilayers is opposite in sign to the spin Hall theory prediction but instead consistent with the orbital Hall theory, which unambiguously confirms the orbital torque generated by the orbital Hall effect. Our finding opens a possibility of utilizing the orbital current for spintronic device applications, and it will invigorate researches on spin-orbit-coupled phenomena based on orbital engineering. [1] Phys. Rev. B 77, 165117 (2008), Phys. Rev. Lett. 102, 016601 (2009). [2] Phys. Rev. Res. 2, 013177 (2020), arXiv: 2107.08478. [3] Nat. Comm. 12, 6710 (2021).
12205-71
Author(s): Sachin Krishnia, Vincent Cros, Sophie Collin, Jean-Marie George, Henri-Yves Jaffrès, Unité Mixte de Physique CNRS/Thales (France)
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Very recently, a dramatic increase in magnetic torque has been observed in ferrimagnetic insulators interfaced with CuOx and the results are explained in the framework of orbital-current generation and emission from CuOx. The conversion of charge-current into the orbital current is governed via the orbital Hall or orbital Rashba effect, a similar analogy to the spin Hall and Rashba effect. In this talk, we will present our latest results on the observation of damping-like torque in Co/CuOx without any heavy-metal layer due to orbital Rashba effect at Co/CuOx interface. Furthermore, we observe a two-fold increase in damping-like torques in Co(2)/Pt(4)/Cu/CuOx(3) that further validates our hypothesis.
12205-72
Author(s): Chen-Yu Hu, Yu-Fang Chiu, Chia-Chin Tsai, Chao-Chun Huang, Kuan-Hao Chen, Cheng-Wei Peng, National Taiwan Univ. (Taiwan); Chien-Min Lee, Ming-Yuan Song, Yen-Lin Huang, Shy-Jay Lin, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan); Chi-Feng Pai, National Taiwan Univ. (Taiwan)
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5d transition metal Pt is one of the classical spin Hall materials for efficient generation of spin-orbit torques (SOTs) in Pt/ferromagnetic layer (FM) heterostructures. However, for a long while with tremendous engineering endeavors, the damping-like SOT efficiencies (ξDL) of Pt and Pt alloys are still limited to ξDL<0.5. Here we present that with proper alloying elements, particularly 3d transition metals V and Cr, the strength of the high spin Hall conductivity of Pt (σSH∼6.45×105(ℏ/2e)Ω−1⋅m−1) can be developed. Especially for the Cr-doped case, an extremely high ξDL∼0.9 in a Pt0.69Cr0.31/Co device can be achieved with a moderate Pt0.69Cr0.31 resistivity of ρxx∼133μΩ⋅cm. A low critical SOT-driven switching current density of Jc∼3.16×106A⋅cm−2 is also demonstrated. The damping constant (α) of Pt0.69Cr0.31/FM structure is also found to be reduced to 0.052 from the pure Pt/FM case of 0.078. The overall high σSH, giant ξDL, moderate ρxx, and reduced α of such Pt-Cr/FM heterostructure makes it promising for versatile extremely low power consumption SOT memory applications.
12205-73
Author(s): Takashi Kikkawa, The Univ. of Tokyo (Japan); Derek Reitz, Univ. of California, Los Angeles (United States); Hiroaki Ito, Takahiko Makiuchi, Takahiro Sugimoto, Kakeru Tsunekawa, Shunsuke Daimon, The Univ. of Tokyo (Japan); Koichi Oyanagi, Iwate Univ. (Japan); Rafael Ramos, Univ. de Santiago de Compostela (Spain); Saburo Takahashi, Tohoku Univ. (Japan); Yuki Shiomi, The Univ. of Tokyo (Japan); Yaroslav Tserkovnyak, Univ. of California, Los Angeles (United States); Eiji Saitoh, The Univ. of Tokyo (Japan)
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We report thermoelectric generation caused by nuclear spins in a solid: nuclear-spin Seebeck effect. The sample is a magnetically ordered material MnCO3 having a large nuclear spin (I = 5/2) of 55Mn nuclei and strong hyperfine coupling, with a Pt contact. In the system, we observe low-temperature thermoelectric signals down to 100 mK due to nuclear-spin excitation. The results were quantitatively reproduced by a theoretical calculation in which interfacial Korringa process is taken into consideration. The nuclear thermoelectric effect demonstrated here offers a new way for exploring thermoelectric science and technologies at ultralow temperatures.
Session 18: Quantum Spintronics Theory
12205-74
Author(s): Branislav Nikolic, Univ. of Delaware (United States)
12205-75
Author(s): Alberto Crepaldi, Politecnico di Milano (Italy)
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In chiral crystals, the absence of inversion and mirror symmetry is responsible for unconventional spin properties and the emergence of exotic topological fermions [1]. Trigonal tellurium is one of the simplest chiral crystals, and by using spin-and-angle-resolved photoemission spectroscopy (srARPES) we have recently reported signatures of composite, accordionlike and Kramers-Weyl (KW) fermions in its band structure [2]. In contrast to conventional Weyl fermions that arise from band inversion, and are thereby degenerate in energy, KW points with opposite topological charges are pinned at different energies and at different time-reversal invariant momenta (TRIM) by the action of time-reversal symmetry. In KW fermions the spin is predicted to lie parallel to the wavevector, thus realizing a hedgehog texture [1]. In our study we clarify that the radial spin texture is not a prerogative of the KW fermions, but it can be observed also at non-TRIM point [2], as confirmed by an independent srARPES study of the spin properties around the H point of Te [3]. This is made possible by the presence of multiple rotational axes, combined with the breaking of mirror symmetry. Our results illustrate how the arrangement of spin in the reciprocal space is a consequence of the local point group symmetry, and it does not reflect only global properties of the crystal. Spin texture more complex than hedgehog-like can be stabilized, sharing common features with the arrangement taken in Skyrmions by magnetic momenta in real space [3, 4]. These spin textures are important ingredient to explain the chiral induced spin selectivity (CISS) effect that might find application in spintronics devices [5]; hence a complete classification of the spin texture for all local point group symmetries is highly demanded. [1] G. Chang et al., Nat. Mater. 17, 978 (2018) [2] G. Gatti et al., Phys. Rev. Lett. 125, 216402 (2020) [3] M. Sakano et al., Phys. Rev. Lett. 124, 136404 (2020) [4] C.M. Acosta et al., Phys. Rev. B 104, 104408 (2021) [5] S. Dalum and P. Hedegård, Nano Lett. 19, 5253 (2019)
12205-76
Author(s): Masud Mansuripur, Wyant College of Optical Sciences (United States)
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The Einstein-Podolsky-Rosen (EPR) paradox that argues for the incompleteness of quantum mechanics as a description of physical reality has been put to rest by John Bell's famous theorem. Nevertheless, in his writings and public presentations, Richard Feynman never acknowledged the significance of Bell's theorem. In this paper, I will discuss several variants of the Bell inequalities (including one that was specifically espoused by Feynman), and explore the ways in which they demolish the arguments in favor of hidden-variable theories. I will also examine the roots of Feynman's attitude toward Bell's theorem in the context of Feynman's special perspective on quantum mechanics.
12205-77
Author(s): Tharnier Puel, The Univ. of Iowa (United States); Stefano Chesi, Beijing Computational Science Research Ctr. (China); Stefan Kirchner, Zhejiang Institute of Modern Physics, Zhejiang Univ. (China); Pedro Ribeiro, CeFEMA, Instituto Superior Técnico (Portugal)
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Far-from-equilibrium quantum states are routinely realized in mesoscopic solid-state devices and cold atomic gas settings. Thus it is timely to explore the properties of phases of current-carrying matter and address the conditions which have to be met for their emergence. Especially in low-dimensional systems, it has long been recognized that thermodynamic phases are generally suppressed due to the enhanced role of quantum fluctuations. Our findings exemplify that out-of-equilibrium conditions allow for novel critical phenomena which are not possible in equilibrium. In this talk, we explore the non-equilibrium steady-state of an XY spin chain, as well as a chain of hard-core bosons. The non-equilibrium condition is driven by thermal reservoirs coupled to the central system at its ends.
12205-78
Author(s): Adonai Rodrigues da Cruz, Technische Univ. Eindhoven (Netherlands); Michael E. Flatté, The Univ. of Iowa (United States)
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The combination of spin-orbit coupling with broken spatial inversion symmetry in semiconductors (e.g. zinc-blende quantum-wells and surfaces) and localized spin states originated from a single magnetic defect is a promising system to realize future semiconductor spintronics devices [1]. We present a theory of dissipationless circulating current induced by a magnetic defect in a two-dimensional electron gas with both Bychkov-Rashba and Dresselhaus spin-orbit coupling [1]. The shape and spatial extent of these dissipationless circulating currents depend dramatically on the relative strengths of spin-orbit fields with differing spatial symmetry, offering the potential to use an electric gate to manipulate nanoscale magnetic fields and couple magnetic defects. The spatial structure of the fringing magnetic field emerging from the current is calculated and provides a direct way to measure the spin-orbit fields of the host, as well as the defect spin orientation, through scanning nanoscale magnetometry [3]. [1] Wolfowicz, G., Heremans, F.J., Anderson, C.P. et al. Nat RevMater 6, 906–925 (2021). [2] Da Cruz, A.R. and Flatté, M. E., arXiv:2111.06770 [3] Casola, F. and van der Sar, T. and Yacoby, A. Nature Reviews Materials, 3 (1), 17088 (2018).
12205-79
Author(s): Maria B. Lifshits, Nikita Averkiev, Ioffe Institute (Russian Federation); Dmytro But, Institute of High Pressure Physics (Poland); Wojciech Knap, Institute of High Pressure Physics (Poland)
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We present the results of theoretical studies of dynamic nuclear polarization in a wide range of high frequencies and strong magnetic fields under electron spin resonance (paramagnetic resonance) conditions for shallow phosphorus donors in silicon. At a low temperature there is a significant difference in the populations of the electron spin sublevels, and a high degree of nuclear polarization occurs at relatively weak pump level. We show that nuclear polarization time constants are always different from cross relaxation times and usually depend on the degree of paramagnetic transition saturation. The one-phonon transitions due to modulation of the electron g-factor provide the main mechanism of electron spin relaxation in the system. The efficiency of dynamic nuclear polarization for impurities in silicon is determined by a single parameter depending on the type of impurity (the magnitude of the hyperfine interaction).
Poster Session
Conference attendees are invited to view a collection of posters within the topics of Nanoscience + Engineering, Organic Photonics + Electronics, and Optical Engineering + Applications. Enjoy light refreshments, ask questions, and network with colleagues in your field. Authors of poster papers will be present to answer questions concerning their papers. Attendees are required to wear their conference registration badges to the poster session.

Poster authors, visit Poster Presentation Guidelines for set-up instructions.
12205-80
Author(s): Boris Khots, Dmitriy Khots, Self Employment (United States)
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This paper considers classic Lie group U(1) - the set of all complex numbers with module 1. We prove here that from Observer’s Mathematics point of view the set U(1) is not a group. We proved here the following theorems: Theorem 1. The set U (1) in Observer's Mathematics is not a symmetry group or gauge group of electromagnetism. The probabilities of Maxwell equations invariance under U (1) transformations are less than 1. Theorem 2. The set U (1) in Observer's Mathematics is not a symmetry group or gauge group of Yang-Mills electromagnetism. The probabilities of Yang-Mills equations invariance under U (1) transformations are less than 1.
Sunday Evening Plenary
21 August 2022 • 6:00 PM - 7:30 PM
12198-501
Author(s): Michael W. Berns, Beckman Laser Institute and Medical Clinic (United States)
21 August 2022 • 6:05 PM - 6:35 PM
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It was 1966 and all I knew about lasers was that Goldfinger was going to slice James Bond in half. Then one of my professors at Cornell told me that the department had purchased a small ruby laser but did not know what to do with it and he felt it might be useful for very fine tissue ablation if coupled to a microscope. But the operating parameters of the red ruby laser made it difficult to control when focused to a small spot plus the absorption characteristics of most of the cell structures did not match the 694.3 nm wavelength of the laser. However, when the blue green argon ion laser was available, the ability to focus the pulsed beam to its diffraction limit plus the absorption properties of some cell structures (and the addition of light-absorbing dyes to these structures) allowed for precise ablation in spots less than 0.5 micrometer diameter, especially the chromosomes in live cells. When the nanosecond and picosecond 532nm and 355 nm harmonics of the NdYag lasers became available even greater precision of nanoablation was possible due to natural absorption by the target structure and/or non-linear multiphoton ablation which occurred regardless of absorption characteristics of the target. These optical systems were used (and still are) to perform subcellular surgery on any cell organelle visible with the light microscope. With Arthur Ashkin’s invention of optical traps (laser tweezers), cell biologists now had a complementary optical tool to the laser scissors and so began a renaissance in the use of light to finely alter and manipulate cells.
12238-502
Quantum science and metrology (Plenary Presentation)
Author(s): Jun Ye, JILA, Univ. of Colorado (United States)
21 August 2022 • 6:45 PM - 7:15 PM
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Precise engineering of quantum states of matter and innovative laser technology are revolutionizing the performance of atomic clocks and metrology, providing new opportunities to explore emerging phenomena, test fundamental symmetry, and search for new physics. The recent work of measuring gravitational time dilation at the sub-millimeter scale highlights exciting prospects for new scientific discovery and technology development.
Nanoscience + Engineering Plenary
22 August 2022 • 8:30 AM - 10:05 AM
Session Chairs: Gennady B. Shvets, Cornell Univ. (United States), Cornelia Denz, Westfälische Wilhelms-Univ. Münster (Germany)
8:30 AM - 8:35 AM: Welcome and Opening Remarks
12203-501
Author(s): Lisa V. Poulikakos, Univ. of California, San Diego (United States)
22 August 2022 • 8:35 AM - 9:10 AM
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The origin and progression of a variety of leading health challenges, encompassing Alzheimer’s disease, heart disease, fibrosis and cancer, are directly linked to changes in the presence and orientation of fibrous matter in biological tissue. Here, we leverage the unique properties of anisotropic, colorimetric metasurfaces to scale down the complex manipulation of light and selectively visualize disease-relevant fiber density and orientation in biological tissue. Starting with the example of breast cancer diagnostics, we then expand our view to the rich palette of fiber-affecting diseases where metasurfaces hold great potential as rapid, precise and low-cost tissue diagnostics with facile clinical implementation.
12204-502
Author(s): Keren Bergman, Columbia Univ. (United States)
22 August 2022 • 9:20 AM - 9:55 AM
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High performance data centers are increasingly bottlenecked by the energy and communications costs of interconnection networks. Our recent work has shown how integrated silicon photonics with comb-driven dense wavelength-division multiplexing can scale to realize Pb/s chip escape bandwidths with sub-picojoule/bit energy consumption. We use this emerging interconnect technology to introduce the concept of embedded photonics for deeply disaggregated architectures. Beyond alleviating the bandwidth/energy bottlenecks, the new architectural approach enables flexible connectivity tailored for specific applications.
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
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
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
Hans T. Nembach
National Institute of Standards and Technology (United States)
Program Committee
The Univ. of Tokyo (Japan)
Program Committee
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