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 12205

Spintronics XV

21 - 25 August 2022 | Conv. Ctr. Room 6D (and 6C for Session 19)
View Session ∨
  • 1: THz Spintronics
  • 2: Topological Spintronics I
  • 3: Topological Spintronics II
  • 4: Ferromagnetic Resonance and THz spintronics
  • Sunday Evening Plenary
  • Nanoscience + Engineering Plenary
  • 5: MRAMs and Sensors
  • 6: MRAMs and Spintronics Devices
  • 7: Spin Photonics
  • Poster Session
  • 8: Van der Waals Spintronics
  • 9: Neuromorphic Computing I
  • 10: Neuromorphic Computing II
  • 11: Spin-Hall Effect and Spin-Orbit Torque
  • 12: Coherence and Ballistic Transport
  • 13: Superconducting and Voltage-Controlled Spintronics
  • 14: Spin Lasers
  • 15: Nanomagnetism and Magnonics
  • 16: Orbital Torque and Spin Seebeck Effect
  • 17: Time-resolved spectroscopy and Magnetic Imaging
  • 18: Voltage-Controlled Spintronics
  • 19: Quantum Spintronics Theory
Session 1: THz Spintronics
21 August 2022 • 8:30 AM - 10:00 AM PDT | Conv. Ctr. Room 6D
Session Chair: Henri-Yves Jaffrès, Unité Mixte de Physique CNRS/Thales (France)
12205-2
Author(s): Y. Hirai, The Univ.of Tokyo (Japan); N. Yoshikawa, H. Hirose, M. Kawaguchi, M. Hayashi, R. Shimano, The Univ. of Tokyo (Japan)
On demand | Presented live 21 August 2022
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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.
PC12205-3
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, Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Universi (France); Thi Huong Dang, Unité Mixte de Physique CNRS, Thales, Université 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, Ctr. de Nanosciences et de Nanotechnologies, Université Paris-Saclay, CNRS (France); 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)
21 August 2022 • 9:00 AM - 9:30 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-4
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)
21 August 2022 • 9:30 AM - 10:00 AM PDT | Conv. Ctr. Room 6D
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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
21 August 2022 • 10:25 AM - 12:25 PM PDT | Conv. Ctr. Room 6D
Session Chair: Matthias Benjamin Jungfleisch, Univ. of Delaware (United States)
12205-5
Author(s): James H. Cullen, The Univ. of New South Wales (Australia); Rhonald Burgos Atencia, Univ. del Sinú (Colombia); Dimitrie Culcer, The Univ. of New South Wales (Australia)
On demand | Presented live 21 August 2022
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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.
PC12205-6
Author(s): Alexey Belyanin, Texas A&M Univ. (United States)
21 August 2022 • 10:55 AM - 11:25 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-7
Author(s): Edwin Fohtung, Xiaowen Shi, Rensselaer Polytechnic Institute (United States); Dmitry Karpov, European Synchrotron Radiation Facility (France)
21 August 2022 • 11:25 AM - 11:55 AM PDT | Conv. Ctr. Room 6D
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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
PC12205-8
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)
21 August 2022 • 11:55 AM - 12:25 PM PDT | Conv. Ctr. Room 6D
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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
21 August 2022 • 1:25 PM - 2:25 PM PDT | Conv. Ctr. Room 6D
Session Chair: Dimitrie Culcer, The Univ. of New South Wales (Australia)
PC12205-10
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)
21 August 2022 • 1:25 PM - 1:55 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-12
Author(s): Jukka Vayrynen, Purdue Univ. (United States)
21 August 2022 • 1:55 PM - 2:25 PM PDT | Conv. Ctr. Room 6D
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Majorana states hosted in vortex cores of topological insulator/superconductor heterostructures present a promising alternative to nanowire-based approaches. Vortices can be pinned to anti-dots pre-fabricated in the superconductor; large anti-dots are relatively simple to fabricate and ensure that weak magnetic fields are sufficient to induce a required quantum of flux. However, it has thus far been unclear whether current topological insulator materials are clean enough to sustain Majorana vortex modes with a sizable gap to excitations. Also, if the anti-dot is too large, the level spacing of subgap vortex states may become too small even in a clean case. In this work, we study numerically the vortex subgap spectrum as a function of disorder, chemical potential, and the anti-dot size. We employ a two-dimensional low-energy description of the topological insulator surface, which allows as to simulate large quantum systems with vortices up to 1 micron in diameter. We connect our results to existing mobility measurement data to translate the level of disorder in existing materials to our simulated disorder model.
Session 4: Ferromagnetic Resonance and THz spintronics
21 August 2022 • 2:50 PM - 4:20 PM PDT | Conv. Ctr. Room 6D
Session Chair: Mehmet A. Noyan, U.S. Naval Research Lab. (United States)
PC12205-14
Author(s): Rudolf Bratschitsch, Westfälische Wilhelms-Univ. Münster (Germany)
21 August 2022 • 2:50 PM - 3:20 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-15
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)
21 August 2022 • 3:20 PM - 3:50 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-16
Author(s): Stefan Mathias, Georg-August-Univ. Göttingen (Germany)
21 August 2022 • 3:50 PM - 4:20 PM PDT | Conv. Ctr. Room 6D
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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.
Sunday Evening Plenary
21 August 2022 • 6:00 PM - 7:25 PM PDT | Conv. Ctr. Room 6A
Session Chair: Anita Mahadevan-Jansen, SPIE 2022 President, Vanderbilt Univ. (United States)

6:00 PM - 6:05 PM: Welcome and Opening Remarks
PC12198-501
Author(s): Michael W. Berns, Beckman Laser Institute and Medical Clinic (United States)
21 August 2022 • 6:05 PM - 6:35 PM PDT | Conv. Ctr. Room 6A
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In August 2022, about a week before he was due to receive the highest honor of SPIE - the SPIE Gold Medal, Michael Berns passed away at the age of 79. In place of the talk he had been preparing to give, we are revisiting a wonderfully retrospective talk he gave at the conference last year. ABSTRACT: Little did I know that when I published our first laser microbeam paper on chromosome surgery in 1969, that 50 years later I would still be doing that—trying to explain the inexplicable result we saw back then. The path to an answer of why cells with partially photon-ablated chromosomes could reproduce and maintain the photon-induced deletion in the clonal population of cells, was a path that was solely possible by the parallel development of additional tools in the photonic toolbox. Development of digital-based imaging technologies, GFP-based molecular fluorescent probes, and an evolution of optical manipulation tools (photonic scissors and tweezers) have been combined to provide a tantalizing answer to the question of why cells can divide and form clones following removal of a segment of their DNA.
PC12238-502
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 PDT | Conv. Ctr. Room 6A
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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 PDT | Conv. Ctr. Room 6A
Session Chair: Gennady Shvets, Cornell Univ. (United States)

8:30 AM - 8:35 AM: Welcome and Opening Remarks
PC12203-501
Author(s): Lisa V. Poulikakos, Univ. of California, San Diego (United States)
22 August 2022 • 8:35 AM - 9:10 AM PDT | Conv. Ctr. Room 6A
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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.
PC12204-502
Author(s): Keren Bergman, Columbia Univ. (United States)
22 August 2022 • 9:20 AM - 9:55 AM PDT | Conv. Ctr. Room 6A
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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.
Session 5: MRAMs and Sensors
22 August 2022 • 10:30 AM - 12:40 PM PDT | Conv. Ctr. Room 6D
Session Chair: Dafiné Ravelosona
PC12205-18
Author(s): Hideo Ohno, Shunsuke Fukami, Tohoku Univ. (Japan)
22 August 2022 • 10:30 AM - 11:10 AM PDT | Conv. Ctr. Room 6D
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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
PC12205-19
Author(s): Fred B. Mancoff, Monika Arora, Mark DeHerrera, Sumio Ikegawa, Han K. Lee, Subir Mukherjee, Goei Shimon, Jijun Sun, Iftekhar Rahman, Frederick Neumeyer, Hsuan-Yi Chou, Chin Hoe Tan, Amit Shah, Syed M. Alam, Kerry J. Nagel, Sanjeev Aggarwal, Everspin Technologies, Inc. (United States)
22 August 2022 • 11:10 AM - 11:40 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-20
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)
22 August 2022 • 11:40 AM - 12:10 PM PDT | Conv. Ctr. Room 6D
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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): Piyush Kumar, Siri Narla, Georgia Institute of Technology (United States); Yu-Ching Liao, Intel Corp. (United States); Azad Naeemi, Georgia Institute of Technology (United States)
On demand | Presented live 22 August 2022
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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
22 August 2022 • 2:10 PM - 4:10 PM PDT | Conv. Ctr. Room 6D
Session Chair: Ricardo C. Sousa, Spintec (France)
PC12205-22
Author(s): Thomas D. Boone, Western Digital Corp. (United States)
22 August 2022 • 2:10 PM - 2:40 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-23
Author(s): Dafiné Ravelosona, Spin-Ion Technologies (France), CNRS (France), Univ. Paris Saclay (France)
22 August 2022 • 2:40 PM - 3:10 PM PDT | Conv. Ctr. Room 6D
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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): Henrik Wolframm, Viktor Schell, Eckhard Quandt, Michael Höft, Andreas Bahr, Kiel Univ. (Germany)
On demand | Presented live 22 August 2022
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Typical demands for magnetic field sensor applications are high dynamic magnetic field ranges, ambient temperature operation, small dimensions, necessary for high spatial resolution, and low energy consumption. In the case of biomagnetic sensing very high requirements in case of sensitivity and limit of detection in the pT/Hz^(1/2) to fT/Hz^(1/2) range arise. SAW sensors based on the delta-E effect combine the advantages of small form factor, ambient temperature operation and high sensitivity. The phase change of a transmitted signal serves as a measure of a magnetic field. Very low phase noise read out electronics is required to detect the phase changes.
PC12205-25
Author(s): Martin Bowen, Institut de Physique et de Chimie des Matériaux de Strasbourg (France)
22 August 2022 • 3:40 PM - 4:10 PM PDT | Conv. Ctr. Room 6D
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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: Spin Photonics
22 August 2022 • 4:10 PM - 4:40 PM PDT | Conv. Ctr. Room 6D
Session Chair: Dafiné Ravelosona, Spin-ION Technologies (France)
PC12205-47
Author(s): Henri-Jean Drouhin, LSI, CEA/DRF/IRAMIS, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris (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)
22 August 2022 • 4:10 PM - 4:40 PM PDT | Conv. Ctr. Room 6D
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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.
Poster Session
22 August 2022 • 5:30 PM - 7:30 PM PDT | Conv. Ctr. Exhibit Hall B1
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.
PC12205-80
Author(s): Boris Khots, Dmitriy Khots, Self Employment (United States)
22 August 2022 • 5:30 PM - 7:30 PM PDT | Conv. Ctr. Exhibit Hall B1
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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.
Session 8: Van der Waals Spintronics
23 August 2022 • 8:00 AM - 10:20 AM PDT | Conv. Ctr. Room 6D
Session Chair: Jean-Eric Wegrowe, Ecole Polytechnique (France)
PC12205-31
Author(s): Felix Casanova, CIC nanoGUNE (Spain), IKERBASQUE, Basque Foundation for Science (Spain)
23 August 2022 • 8:00 AM - 8:30 AM PDT | Conv. Ctr. Room 6D
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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); Geoffrey Diederich, Univ. of Washington (United States), Intelligence Community Postdoctoral Research Fellowship Program (United States); Avalon H. Dismukes, Xiaoyang Zhu, Columbia University (United States); Ting Cao, Xiaodong Xu, Univ. of Washington (United States)
23 August 2022 • 8:30 AM - 9:00 AM PDT | Conv. Ctr. Room 6D
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The coupling of spin and charge in magnetic semiconductors lies at the heart of the field of spintronics and has attracted significant interest for new computing technologies. In this paper, we will review our recent progress in studying and controlling magneto-exciton coupling in the layered antiferromagnetic semiconductor CrSBr. The anisotropic Wannier-type excitons in this material serve as a sensor of the interlayer magnetic coupling. Using this exciton sensor, we found that the magnetic order is extremely tunable by the application of tensile strain, with a reversible AFM to FM transition occurring at large but experimentally feasible strains. These results establish CrSBr as an exciting platform for harnessing spin-charge-lattice coupling to the 2D limit.
12205-33
Author(s): Xintong Li, Zhida Liu, Yihan Liu, Suyogya Karki, Xiaoqin Li, Deji Akinwande, Jean Anne Incorvia, The Univ. of Texas at Austin (United States)
On demand | Presented live 23 August 2022
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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.
PC12205-9
Author(s): Oliver Rader, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany)
23 August 2022 • 9:30 AM - 10:00 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-82
CANCELED: Build-up of spin polarization due to spin dependent charge transfer in MoSe2/hBN/Ni hybrid structures
Author(s): Pierre Renucci, Hans Tornatzky, Cedric Robert, Bo Han, LPCNO INSA Toulouse (France); Thomas Blon, Benjamin Lassagne, Géraldine Ballon, Lab. de Physique et Chimie des Nano-objets (France), Institut National des Sciences Appliquées de Toulouse (France); Yuan Lu, Institut Jean Lamour, UMR 7198, CNRS-Université de Lorraine, BP 239 (France); Kenji Watanabe, Research Center for Functional Materials, National Institute for Materials Science (Japan); Takashi Taniguchi, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, (Japan); Bernhard Urbaszek, LPCNO INSA Toulouse (France); Joao Marcelo Lopes, Paul-Drude-Institut für Festkörperelektronik,Leibniz-Institut im Forschungsverbund Berlin e.V (Germany); Xavier Marie, LPCNO INSA Toulouse (France)
23 August 2022 • 10:00 AM - 10:20 AM PDT | Conv. Ctr. Room 6D
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We present magneto-photoluminescence measurements on a hybrid MoSe2/hBN/Ni heterostructure. When the Nickel layer is magnetized, we observe circularly polarized photoluminescence of the trion peak in MoSe2 monolayer under linearly polarized excitation. This build-up of circular polarization Pc can reach about 4% when the Ni magnetization is saturated, and changes its sign when the magnetization is reversed. Pc decreases when the hBN thickness increases. These results are attributed to a spin-dependent charge transfer between the MoSe2 monolayer and the Nickel film. The build-up of Pc is observed up to 120 K, mainly limited by the trion emission that vanishes with temperature.
Session 9: Neuromorphic Computing I
23 August 2022 • 10:50 AM - 12:20 PM PDT | Conv. Ctr. Room 6D
Session Chair: Damien Querlioz, Univ. Paris-Saclay (France)
PC12205-26
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)
23 August 2022 • 10:50 AM - 11:20 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-27
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)
23 August 2022 • 11:20 AM - 11:50 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-28
Author(s): Alexander 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)
23 August 2022 • 11:50 AM - 12:20 PM PDT | Conv. Ctr. Room 6D
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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.
Session 10: Neuromorphic Computing II
23 August 2022 • 1:50 PM - 3:20 PM PDT | Conv. Ctr. Room 6D
Session Chair: Joseph S. Friedman, The Univ. of Texas at Dallas (United States)
PC12205-29
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)
23 August 2022 • 1:50 PM - 2:20 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-30
Author(s): Chloé Chopin, Simon de Wergifosse, Flavio Abreu Araujo, Univ. Catholique de Louvain (Belgium)
23 August 2022 • 2:20 PM - 2:50 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-81
Author(s): Damien Querlioz, Univ. Paris-Saclay (France)
23 August 2022 • 2:50 PM - 3:20 PM PDT | Conv. Ctr. Room 6D
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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 11: Spin-Hall Effect and Spin-Orbit Torque
23 August 2022 • 3:50 PM - 5:20 PM PDT | Conv. Ctr. Room 6D
Session Chair: Giti A. Khodaparast, Virginia Polytechnic Institute and State Univ. (United States)
PC12205-34
Author(s): Yunqiu Kelly Luo, Cornell Univ. (United States)
23 August 2022 • 3:50 PM - 4:20 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-35
Author(s): Anastasiia Moskaltsova, Timo Kuschel, Univ. Bielefeld (Germany)
23 August 2022 • 4:20 PM - 4:50 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-36
Author(s): Jean-Eric Wegrowe, Ecole Polytechnique (France)
23 August 2022 • 4:50 PM - 5:20 PM PDT | Conv. Ctr. Room 6D
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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 12: Coherence and Ballistic Transport
24 August 2022 • 8:00 AM - 10:00 AM PDT | Conv. Ctr. Room 6D
Session Chair: Jason Robinson, Univ. of Cambridge (United Kingdom)
PC12205-38
Author(s): Michael E. Flatté, The Univ. of Iowa (United States)
24 August 2022 • 8:00 AM - 8:30 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-39
Author(s): Valentin Desbuis, Daniel Lacour, Institut Jean Lamour (France); Corialan 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)
24 August 2022 • 8:30 AM - 9:00 AM PDT | Conv. Ctr. Room 6D
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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 Buffalo (United States), Univ. at Albany (United States); David Hucul, Kathy-Anne Soderberg, United States Air Force Research Lab., Rome (United States), Innovare Advancement Ctr. (United States)
On demand | Presented live 24 August 2022
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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.
PC12205-41
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)
24 August 2022 • 9:30 AM - 10:00 AM PDT | Conv. Ctr. Room 6D
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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 13: Superconducting and Voltage-Controlled Spintronics
24 August 2022 • 10:25 AM - 12:25 PM PDT | Conv. Ctr. Room 6D
Session Chair: Michael E. Flatté, The Univ. of Iowa (United States)
PC12205-56
Author(s): Jayasimha Atulasimha, Virginia Commonwealth Univ. (United States)
24 August 2022 • 10:25 AM - 10:55 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-55
Author(s): Pedram Khalili, Northwestern Univ. (United States)
24 August 2022 • 10:55 AM - 11:25 AM PDT | Conv. Ctr. Room 6D
PC12205-51
Author(s): Matthias Althammer, Walter Schottky Institut, Bayerische Akademie der Wissenschaften (Germany)
24 August 2022 • 11:25 AM - 11:55 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-54
Author(s): Jason Robinson, Univ. of Cambridge (United Kingdom)
24 August 2022 • 11:55 AM - 12:25 PM PDT | Conv. Ctr. Room 6D
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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: Spin Lasers
24 August 2022 • 1:50 PM - 3:50 PM PDT | Conv. Ctr. Room 6D
Session Chair: Christopher H. Marrows, Univ. of Leeds (United Kingdom)
PC12205-42
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)
24 August 2022 • 1:50 PM - 2:20 PM PDT | Conv. Ctr. Room 6D
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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)
On demand | Presented live 24 August 2022
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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.
12205-46
Author(s): Mariusz Drong, LSI, CEA/DRF/IRAMIS, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris (France), VSB-Technical Univ. of Ostrava (Czech Republic); Tibor Fördös, VSB-Technical Univ. of Ostrava (Czech Republic); Henri Y. Jaffrès, Unité Mixte de Physique CNRS/Thales and Univ. Paris-Saclay (France); Kamil Postava, VSB-Technical Univ. of Ostrava (Czech Republic); Henri-Jean Drouhin, Ecole Polytechnique, Institut Polytechnique de Paris (France)
On demand | Presented live 24 August 2022
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Spin-VCSELs offer particularly rich polarization dynamics due to non-trivial interplay of spin-induced circular gain dichroism with microcavity-related linear anisotropies. Over the years, modeling of spin-VCSELs has been basically monopolized by spin-flip model with phase and loss anisotropy. The aim of this work is to explore the role of linear gain anisotropy and asymmetric light confinement within QWs of spin-VCSELs using the extended spin-flip model. We emphasize the existence of exceptional points which are practically accessible due to linear gain anisotropy. Two important consequences of exceptional points are discussed: the polarization phase transition and frequency comb generation.
12205-76
Author(s): Masud Mansuripur, The Univ. of Arizona (United States)
On demand | Presented live 24 August 2022
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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, which inspired numerous experimental tests and brought about further affirmations of quantum reality. Nevertheless, in his writings and public presentations, Richard Feynman never acknowledged the significance of Bell’s contribution to the resolution of the EPR paradox. In this paper, we 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 local hidden-variable theories. We also examine the roots of Feynman’s attitude toward Bell’s theorem in the context of Feynman’s special perspective on quantum mechanics.
Session 15: Nanomagnetism and Magnonics
24 August 2022 • 4:15 PM - 5:45 PM PDT | Conv. Ctr. Room 6D
Session Chair: Matthias Althammer, Walter Schottky Institut (Germany)
PC12205-65
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 Institute (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)
24 August 2022 • 4:15 PM - 4:45 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-61
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)
24 August 2022 • 4:45 PM - 5:15 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-66
Author(s): Kyung-Jin Lee, KAIST (Korea, Republic of)
24 August 2022 • 5:15 PM - 5:45 PM PDT | Conv. Ctr. Room 6D
Session 16: Orbital Torque and Spin Seebeck Effect
25 August 2022 • 8:00 AM - 10:30 AM PDT | Conv. Ctr. Room 6D
Session Chair: Hyunsoo Yang, National Univ. of Singapore (Singapore)
Session 16 runs concurrently with session 19
PC12205-69
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)
25 August 2022 • 8:00 AM - 8:30 AM PDT | Conv. Ctr. Room 6D
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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).
PC12205-70
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)
25 August 2022 • 8:30 AM - 9:00 AM PDT | Conv. Ctr. Room 6D
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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).
PC12205-71
Author(s): Sachin Krishnia, Vincent Cros, Sophie Collin, Jean-Marie George, Henri-Yves Jaffrès, Unité Mixte de Physique CNRS/Thales (France)
25 August 2022 • 9:00 AM - 9:30 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-72
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)
25 August 2022 • 9:30 AM - 10:00 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-73
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)
25 August 2022 • 10:00 AM - 10:30 AM PDT | Conv. Ctr. Room 6D
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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 17: Time-resolved spectroscopy and Magnetic Imaging
25 August 2022 • 10:55 AM - 12:25 PM PDT | Conv. Ctr. Room 6D
Session Chair: Daniel Lacour, Institut Jean Lamour (France)
PC12205-68
Author(s): Kyusup Lee, Hyunsoo Yang, National Univ. of Singapore (Singapore)
25 August 2022 • 10:55 AM - 11:25 AM PDT | Conv. Ctr. Room 6D
PC12205-63
Author(s): Daniel Lacour, K. Ait Oukaci, Institut Jean Lamour (France); D. 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)
25 August 2022 • 11:25 AM - 11:55 AM PDT | Conv. Ctr. Room 6D
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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.
PC12205-64
Author(s): Pauli Kehayias, Sandia National Labs. (United States)
25 August 2022 • 11:55 AM - 12:25 PM PDT | Conv. Ctr. Room 6D
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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 18: Voltage-Controlled Spintronics
25 August 2022 • 1:40 PM - 2:40 PM PDT | Conv. Ctr. Room 6D
Session Chair: Henri-Jean M. Drouhin, Lab. des Solides Irradiés (France)
PC12205-57
Author(s): Christian C. Rinaldi, Politecnico di Milano (Italy)
25 August 2022 • 1:40 PM - 2:10 PM PDT | Conv. Ctr. Room 6D
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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.
PC12205-59
Author(s): Aurélie Kandazoglou, CEA-DRF, Spintec (France); Cécile Grezes, Maxen Cosset-Chéneau, CEA, Spintec (France); Luis Moreno Vincente-Arche, Unité Mixte de Physique CNRS/Thales (France); Paolo Sgarro, CEA, Spintec (France); Paul Noël, ETH Zurich (Switzerland); Stéphane Auffret, Kévin Garello, CEA, Spintec (France); Manuel Bibes, Unité Mixte de Physique CNRS/Thales (France); Laurent Vila, Jean-Philippe Attané, CEA, Spintec (France)
25 August 2022 • 2:10 PM - 2:40 PM PDT | Conv. Ctr. Room 6D
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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 19: Quantum Spintronics Theory
25 August 2022 • 8:00 AM - 10:00 AM PDT | Conv. Ctr. Room 6C
Session Chair: Branislav Nikolic, Univ. of Delaware (United States)
Session 19 runs concurrently with session 16
PC12205-74
Author(s): Branislav Nikolic, Univ. of Delaware (United States)
25 August 2022 • 8:00 AM - 8:30 AM PDT | Conv. Ctr. Room 6C
PC12205-75
Author(s): Alberto Crepaldi, Politecnico di Milano (Italy)
25 August 2022 • 8:30 AM - 9:00 AM PDT | Conv. Ctr. Room 6C
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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)
PC12205-77
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)
25 August 2022 • 9:00 AM - 9:30 AM PDT | Conv. Ctr. Room 6C
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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.
PC12205-78
Author(s): Adonai Rodrigues da Cruz, Technische Univ. Eindhoven (Netherlands); Michael E. Flatté, The Univ. of Iowa (United States)
25 August 2022 • 9:30 AM - 10:00 AM PDT | Conv. Ctr. Room 6C
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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).
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)
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Politecnico di Milano (Italy)
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Univ. of Cambridge (United Kingdom)
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Los Alamos National Lab. (United States)
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Unité Mixte de Physique CNRS/Thales (France)
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Univ. of Rochester (United States)
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Univ. of Victoria (Canada)
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Univ. Montpellier 2 (France)
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The Univ. of Iowa (United States)
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The Univ. of Texas at Dallas (United States)
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ETH Zurich (Switzerland)
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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)
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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
Institut Jean Lamour (France)
Program Committee
U.S. Naval Research Lab. (United States)
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King Abdullah Univ. of Science and Technology (Saudi Arabia)
Program Committee
INSA - Univ. of Toulouse (France)
Program Committee
Laurens W. Molenkamp
Julius-Maximilians-Univ. Würzburg (Germany)
Program Committee
National Institute of Standards and Technology (United States)
Program Committee
The Univ. of Tokyo (Japan)
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Univ. of Minnesota, Twin Cities (United States)
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Institut d'Électronique Fondamentale (France)
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Institut NÉEL (France)
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Martin-Luther-Univ. Halle-Wittenberg (Germany)
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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
Univ. at Buffalo (United States)