1
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Cui X, Mylnikov V, Johansson P, Käll M. Synchronization of optically self-assembled nanorotors. SCIENCE ADVANCES 2024; 10:eadn3485. [PMID: 38457509 PMCID: PMC10923511 DOI: 10.1126/sciadv.adn3485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 02/05/2024] [Indexed: 03/10/2024]
Abstract
Self-assembly of nanoparticles by means of interparticle optical forces provides a compelling approach toward contact-free organization and manipulation of nanoscale entities. However, exploration of the rotational degrees of freedom in this process has remained limited, primarily because of the predominant focus on spherical nanoparticles, for which individual particle orientation cannot be determined. Here, we show that gold nanorods, which self-assemble in water under the influence of circularly polarized light, exhibit synchronized rotational motion at kilohertz frequencies. The synchronization is caused by strong optical interactions and occurs despite the presence of thermal diffusion. Our findings elucidate the intricate dynamics arising from the transfer of photon spin angular momentum to optically bound matter and hold promise for advancing the emerging field of light-driven nanomachinery.
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Affiliation(s)
- Ximin Cui
- Department of Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen 518060, China
| | - Vasilii Mylnikov
- Department of Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden
| | - Peter Johansson
- School of Science and Technology, Örebro University, 701 82 Örebro, Sweden
| | - Mikael Käll
- Department of Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden
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2
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Behera N, Chaurasiya AK, González VH, Litvinenko A, Bainsla L, Kumar A, Khymyn R, Awad AA, Fulara H, Åkerman J. Ultra-Low Current 10 nm Spin Hall Nano-Oscillators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2305002. [PMID: 37990141 DOI: 10.1002/adma.202305002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 10/19/2023] [Indexed: 11/23/2023]
Abstract
Nano-constriction based spin Hall nano-oscillators (SHNOs) are at the forefront of spintronics research for emerging technological applications, such as oscillator-based neuromorphic computing and Ising Machines. However, their miniaturization to the sub-50 nm width regime results in poor scaling of the threshold current. Here, it shows that current shunting through the Si substrate is the origin of this problem and studies how different seed layers can mitigate it. It finds that an ultra-thin Al2 O3 seed layer and SiN (200 nm) coated p-Si substrates provide the best improvement, enabling us to scale down the SHNO width to a truly nanoscopic dimension of 10 nm, operating at threshold currents below 30 μ $\umu$ A. In addition, the combination of electrical insulation and high thermal conductivity of the Al2 O3 seed will offer the best conditions for large SHNO arrays, avoiding any significant temperature gradients within the array. The state-of-the-art ultra-low operational current SHNOs hence pave an energy-efficient route to scale oscillator-based computing to large dynamical neural networks of linear chains or 2D arrays.
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Affiliation(s)
- Nilamani Behera
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
| | | | - Victor H González
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
| | - Artem Litvinenko
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
| | - Lakhan Bainsla
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
- Department of Physics, Indian Institute of Technology Ropar, Roopnagar, 140001, India
| | - Akash Kumar
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Roman Khymyn
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
| | - Ahmad A Awad
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Himanshu Fulara
- Department of Physics, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - Johan Åkerman
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
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3
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Lee O, Wei T, Stenning KD, Gartside JC, Prestwood D, Seki S, Aqeel A, Karube K, Kanazawa N, Taguchi Y, Back C, Tokura Y, Branford WR, Kurebayashi H. Task-adaptive physical reservoir computing. NATURE MATERIALS 2024; 23:79-87. [PMID: 37957266 PMCID: PMC10769874 DOI: 10.1038/s41563-023-01698-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 09/19/2023] [Indexed: 11/15/2023]
Abstract
Reservoir computing is a neuromorphic architecture that may offer viable solutions to the growing energy costs of machine learning. In software-based machine learning, computing performance can be readily reconfigured to suit different computational tasks by tuning hyperparameters. This critical functionality is missing in 'physical' reservoir computing schemes that exploit nonlinear and history-dependent responses of physical systems for data processing. Here we overcome this issue with a 'task-adaptive' approach to physical reservoir computing. By leveraging a thermodynamical phase space to reconfigure key reservoir properties, we optimize computational performance across a diverse task set. We use the spin-wave spectra of the chiral magnet Cu2OSeO3 that hosts skyrmion, conical and helical magnetic phases, providing on-demand access to different computational reservoir responses. The task-adaptive approach is applicable to a wide variety of physical systems, which we show in other chiral magnets via above (and near) room-temperature demonstrations in Co8.5Zn8.5Mn3 (and FeGe).
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Affiliation(s)
- Oscar Lee
- London Centre for Nanotechnology, University College London, London, UK.
| | - Tianyi Wei
- London Centre for Nanotechnology, University College London, London, UK
| | | | | | - Dan Prestwood
- London Centre for Nanotechnology, University College London, London, UK
| | - Shinichiro Seki
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
| | - Aisha Aqeel
- Physik-Department, Technische Universität München, Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Munich, Germany
| | - Kosuke Karube
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - Naoya Kanazawa
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
| | | | - Christian Back
- Physik-Department, Technische Universität München, Garching, Germany
| | - Yoshinori Tokura
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
- Tokyo College, University of Tokyo, Tokyo, Japan
| | - Will R Branford
- Blackett Laboratory, Imperial College London, London, UK
- London Centre for Nanotechnology, Imperial College London, London, UK
| | - Hidekazu Kurebayashi
- London Centre for Nanotechnology, University College London, London, UK.
- Department of Electronic and Electrical Engineering, University College London, London, UK.
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
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4
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Ross A, Leroux N, De Riz A, Marković D, Sanz-Hernández D, Trastoy J, Bortolotti P, Querlioz D, Martins L, Benetti L, Claro MS, Anacleto P, Schulman A, Taris T, Begueret JB, Saïghi S, Jenkins AS, Ferreira R, Vincent AF, Mizrahi FA, Grollier J. Multilayer spintronic neural networks with radiofrequency connections. NATURE NANOTECHNOLOGY 2023; 18:1273-1280. [PMID: 37500772 DOI: 10.1038/s41565-023-01452-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 06/12/2023] [Indexed: 07/29/2023]
Abstract
Spintronic nano-synapses and nano-neurons perform neural network operations with high accuracy thanks to their rich, reproducible and controllable magnetization dynamics. These dynamical nanodevices could transform artificial intelligence hardware, provided they implement state-of-the-art deep neural networks. However, there is today no scalable way to connect them in multilayers. Here we show that the flagship nano-components of spintronics, magnetic tunnel junctions, can be connected into multilayer neural networks where they implement both synapses and neurons thanks to their magnetization dynamics, and communicate by processing, transmitting and receiving radiofrequency signals. We build a hardware spintronic neural network composed of nine magnetic tunnel junctions connected in two layers, and show that it natively classifies nonlinearly separable radiofrequency inputs with an accuracy of 97.7%. Using physical simulations, we demonstrate that a large network of nanoscale junctions can achieve state-of-the-art identification of drones from their radiofrequency transmissions, without digitization and consuming only a few milliwatts, which constitutes a gain of several orders of magnitude in power consumption compared to currently used techniques. This study lays the foundation for deep, dynamical, spintronic neural networks.
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Affiliation(s)
- Andrew Ross
- Unité Mixte de Physique CNRS/Thales, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - Nathan Leroux
- Unité Mixte de Physique CNRS/Thales, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - Arnaud De Riz
- Unité Mixte de Physique CNRS/Thales, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - Danijela Marković
- Unité Mixte de Physique CNRS/Thales, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - Dédalo Sanz-Hernández
- Unité Mixte de Physique CNRS/Thales, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - Juan Trastoy
- Unité Mixte de Physique CNRS/Thales, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - Paolo Bortolotti
- Unité Mixte de Physique CNRS/Thales, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - Damien Querlioz
- Centre de Nanosciences et de Nanotechnologies, Université Paris-Saclay, CNRS, Palaiseau, France
| | - Leandro Martins
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
| | - Luana Benetti
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
| | - Marcel S Claro
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
| | - Pedro Anacleto
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
| | | | - Thierry Taris
- Laboratoire de l'Intégration du Matériau au Système (IMS; UMR 5218), Univ. Bordeaux, CNRS, Bordeaux INP, Talence, France
| | - Jean-Baptiste Begueret
- Laboratoire de l'Intégration du Matériau au Système (IMS; UMR 5218), Univ. Bordeaux, CNRS, Bordeaux INP, Talence, France
| | - Sylvain Saïghi
- Laboratoire de l'Intégration du Matériau au Système (IMS; UMR 5218), Univ. Bordeaux, CNRS, Bordeaux INP, Talence, France
| | - Alex S Jenkins
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
| | - Ricardo Ferreira
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
| | - Adrien F Vincent
- Laboratoire de l'Intégration du Matériau au Système (IMS; UMR 5218), Univ. Bordeaux, CNRS, Bordeaux INP, Talence, France
| | - Frank Alice Mizrahi
- Unité Mixte de Physique CNRS/Thales, CNRS, Thales, Université Paris-Saclay, Palaiseau, France.
| | - Julie Grollier
- Unité Mixte de Physique CNRS/Thales, CNRS, Thales, Université Paris-Saclay, Palaiseau, France.
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5
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Kumar A, Fulara H, Khymyn R, Litvinenko A, Zahedinejad M, Rajabali M, Zhao X, Behera N, Houshang A, Awad AA, Åkerman J. Robust Mutual Synchronization in Long Spin Hall Nano-oscillator Chains. NANO LETTERS 2023. [PMID: 37450893 PMCID: PMC10375588 DOI: 10.1021/acs.nanolett.3c02036] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
Mutual synchronization of N serially connected spintronic nano-oscillators boosts their coherence by N and peak power by N2. Increasing the number of synchronized nano-oscillators in chains holds significance for improved signal quality and emerging applications such as oscillator based unconventional computing. We successfully fabricate spin Hall nano-oscillator chains with up to 50 serially connected nanoconstrictions using W/NiFe, W/CoFeB/MgO, and NiFe/Pt stacks. Our experiments demonstrate robust and complete mutual synchronization of 21 nanoconstrictions at an operating frequency of 10 GHz, achieving line widths <134 kHz and quality factors >79,000. As the number of mutually synchronized oscillators increases, we observe a quadratic increase in peak power, resulting in 400-fold higher peak power in long chains compared to individual nanoconstrictions. While chains longer than 21 nanoconstrictions also achieve complete mutual synchronization, it is less robust, and their signal quality does not improve significantly, as they tend to break into partially synchronized states.
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Affiliation(s)
- Akash Kumar
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Himanshu Fulara
- Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Roman Khymyn
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | - Artem Litvinenko
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | | | | | - Xiaotian Zhao
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | - Nilamani Behera
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | - Afshin Houshang
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | - Ahmad A Awad
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Johan Åkerman
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
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6
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Lee HC, Kim J, Kim HR, Kim KH, Park KJ, So JP, Lee JM, Hwang MS, Park HG. Nanograin network memory with reconfigurable percolation paths for synaptic interactions. LIGHT, SCIENCE & APPLICATIONS 2023; 12:118. [PMID: 37188669 DOI: 10.1038/s41377-023-01168-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 04/15/2023] [Accepted: 04/23/2023] [Indexed: 05/17/2023]
Abstract
The development of memory devices with functions that simultaneously process and store data is required for efficient computation. To achieve this, artificial synaptic devices have been proposed because they can construct hybrid networks with biological neurons and perform neuromorphic computation. However, irreversible aging of these electrical devices causes unavoidable performance degradation. Although several photonic approaches to controlling currents have been suggested, suppression of current levels and switching of analog conductance in a simple photonic manner remain challenging. Here, we demonstrated a nanograin network memory using reconfigurable percolation paths in a single Si nanowire with solid core/porous shell and pure solid core segments. The electrical and photonic control of current percolation paths enabled the analog and reversible adjustment of the persistent current level, exhibiting memory behavior and current suppression in this single nanowire device. In addition, the synaptic behaviors of memory and erasure were demonstrated through potentiation and habituation processes. Photonic habituation was achieved using laser illumination on the porous nanowire shell, with a linear decrease in the postsynaptic current. Furthermore, synaptic elimination was emulated using two adjacent devices interconnected on a single nanowire. Therefore, electrical and photonic reconfiguration of the conductive paths in Si nanograin networks will pave the way for next-generation nanodevice technologies.
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Affiliation(s)
- Hoo-Cheol Lee
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea
| | - Jungkil Kim
- Department of Physics, Jeju National University, Jeju, 63243, Republic of Korea.
| | - Ha-Reem Kim
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea
| | - Kyoung-Ho Kim
- Department of Physics, Chungbuk National University, Cheongju, 28644, Republic of Korea
| | - Kyung-Jun Park
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea
| | - Jae-Pil So
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea
| | - Jung Min Lee
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea
| | - Min-Soo Hwang
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea
| | - Hong-Gyu Park
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea.
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7
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Bhattacharya D, Chen Z, Jensen CJ, Liu C, Burks EC, Gilbert DA, Zhang X, Yin G, Liu K. 3D Interconnected Magnetic Nanowire Networks as Potential Integrated Multistate Memristors. NANO LETTERS 2022; 22:10010-10017. [PMID: 36480011 DOI: 10.1021/acs.nanolett.2c03616] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Interconnected magnetic nanowire (NW) networks offer a promising platform for three-dimensional (3D) information storage and integrated neuromorphic computing. Here we report discrete propagation of magnetic states in interconnected Co nanowire networks driven by magnetic field and current, manifested in distinct magnetoresistance (MR) features. In these networks, when only a few interconnected NWs were measured, multiple MR kinks and local minima were observed, including a significant minimum at a positive field during the descending field sweep. Micromagnetic simulations showed that this unusual feature was due to domain wall (DW) pinning at the NW intersections, which was confirmed by off-axis electron holography imaging. In a complex network with many intersections, sequential switching of nanowire sections separated by interconnects was observed, along with stochastic characteristics. The pinning/depinning of the DWs can be further controlled by the driving current density. These results illustrate the promise of such interconnected networks as integrated multistate memristors.
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Affiliation(s)
| | - Zhijie Chen
- Physics Department, Georgetown University, Washington, D.C.20057, United States
| | | | - Chen Liu
- Physical Science and Engineering Division, King Abdullah University of Science & Technology, Thuwal23955-6900, Saudi Arabia
| | - Edward C Burks
- Physics Department, University of California, Davis, California95618, United States
| | - Dustin A Gilbert
- Department of Materials Science and Engineering, and Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Xixiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science & Technology, Thuwal23955-6900, Saudi Arabia
| | - Gen Yin
- Physics Department, Georgetown University, Washington, D.C.20057, United States
| | - Kai Liu
- Physics Department, Georgetown University, Washington, D.C.20057, United States
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8
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Raab K, Brems MA, Beneke G, Dohi T, Rothörl J, Kammerbauer F, Mentink JH, Kläui M. Brownian reservoir computing realized using geometrically confined skyrmion dynamics. Nat Commun 2022; 13:6982. [DOI: 10.1038/s41467-022-34309-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 10/19/2022] [Indexed: 11/16/2022] Open
Abstract
AbstractReservoir computing (RC) has been considered as one of the key computational principles beyond von-Neumann computing. Magnetic skyrmions, topological particle-like spin textures in magnetic films are particularly promising for implementing RC, since they respond strongly nonlinearly to external stimuli and feature inherent multiscale dynamics. However, despite several theoretical proposals that exist for skyrmion reservoir computing, experimental realizations have been elusive until now. Here, we propose and experimentally demonstrate a conceptually new approach to skyrmion RC that leverages the thermally activated diffusive motion of skyrmions. By confining the electrically gated and thermal skyrmion motion, we find that already a single skyrmion in a confined geometry suffices to realize nonlinearly separable functions, which we demonstrate for the XOR gate along with all other Boolean logic gate operations. Besides this universality, the reservoir computing concept ensures low training costs and ultra-low power operation with current densities orders of magnitude smaller than those used in existing spintronic reservoir computing demonstrations. Our proposed concept is robust against device imperfections and can be readily extended by linking multiple confined geometries and/or by including more skyrmions in the reservoir, suggesting high potential for scalable and low-energy reservoir computing.
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9
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Ernst E. The AI trilemma: Saving the planet without ruining our jobs. Front Artif Intell 2022; 5:886561. [PMID: 36337142 PMCID: PMC9626962 DOI: 10.3389/frai.2022.886561] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 08/12/2022] [Indexed: 01/24/2023] Open
Abstract
Digitalization and artificial intelligence increasingly affect the world of work. Rising risk of massive job losses have sparked technological fears. Limited income and productivity gains concentrated among a few tech companies are fueling inequalities. In addition, the increasing ecological footprint of digital technologies has become the focus of much discussion. This creates a trilemma of rising inequality, low productivity growth and high ecological costs brought by technological progress. How can this trilemma be resolved? Which digital applications should be promoted specifically? And what should policymakers do to address this trilemma? This contribution shows that policymakers should create suitable conditions to fully exploit the potential in the area of network applications (transport, information exchange, supply, provisioning) in order to reap maximum societal benefits that can be widely shared. This requires shifting incentives away from current uses toward those that can, at least partially, address the trilemma. The contribution analyses the scope and limits of current policy instruments in this regard and discusses alternative approaches that are more aligned with the properties of the emerging technological paradigm underlying the digital economy. In particular, it discusses the possibility of institutional innovations required to address the socio-economic challenges resulting from the technological innovations brought about by artificial intelligence.
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Affiliation(s)
- Ekkehard Ernst
- International Labour Organization, Department of Research, Geneva, Switzerland
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10
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Yokouchi T, Sugimoto S, Rana B, Seki S, Ogawa N, Shiomi Y, Kasai S, Otani Y. Pattern recognition with neuromorphic computing using magnetic field-induced dynamics of skyrmions. SCIENCE ADVANCES 2022; 8:eabq5652. [PMID: 36179033 PMCID: PMC9524829 DOI: 10.1126/sciadv.abq5652] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 08/15/2022] [Indexed: 06/12/2023]
Abstract
Nonlinear phenomena in physical systems can be used for brain-inspired computing with low energy consumption. Response from the dynamics of a topological spin structure called skyrmion is one of the candidates for such a neuromorphic computing. However, its ability has not been well explored experimentally. Here, we experimentally demonstrate neuromorphic computing using nonlinear response originating from magnetic field-induced dynamics of skyrmions. We designed a simple-structured skyrmion-based neuromorphic device and succeeded in handwritten digit recognition with the accuracy as large as 94.7% and waveform recognition. Notably, there exists a positive correlation between the recognition accuracy and the number of skyrmions in the devices. The large degrees of freedom of skyrmion systems, such as the position and the size, originate from the more complex nonlinear mapping, the larger output dimension, and, thus, high accuracy. Our results provide a guideline for developing energy-saving and high-performance skyrmion neuromorphic computing devices.
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Affiliation(s)
- Tomoyuki Yokouchi
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Basic Science, The University of Tokyo, Tokyo 152-8902, Japan
| | - Satoshi Sugimoto
- National Institute for Materials Science (NIMS), Tsukuba 305-0047, Japan
| | - Bivas Rana
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University, Poznań, Uniwersytetu Poznanskiego 2, Poznań 61-614, Poland
| | - Shinichiro Seki
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Tokyo 102-0075, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, Japan
| | - Naoki Ogawa
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Tokyo 102-0075, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
| | - Yuki Shiomi
- Department of Basic Science, The University of Tokyo, Tokyo 152-8902, Japan
| | - Shinya Kasai
- National Institute for Materials Science (NIMS), Tsukuba 305-0047, Japan
- PRESTO, Japan Science and Technology Agency (JST), Tokyo 102-0075, Japan
| | - Yoshichika Otani
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa 277-8561, Japan
- Trans-scale Quantum Science Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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11
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Choi JG, Park J, Kang MG, Kim D, Rieh JS, Lee KJ, Kim KJ, Park BG. Voltage-driven gigahertz frequency tuning of spin Hall nano-oscillators. Nat Commun 2022; 13:3783. [PMID: 35773256 PMCID: PMC9246901 DOI: 10.1038/s41467-022-31493-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 06/20/2022] [Indexed: 11/09/2022] Open
Abstract
Spin Hall nano-oscillators (SHNOs) exploiting current-driven magnetization auto-oscillation have recently received much attention because of their potential for neuromorphic computing. Widespread applications of neuromorphic devices with SHNOs require an energy-efficient method of tuning oscillation frequency over broad ranges and storing trained frequencies in SHNOs without the need for additional memory circuitry. While the voltage-driven frequency tuning of SHNOs has been demonstrated, it was volatile and limited to megahertz ranges. Here, we show that the frequency of SHNOs is controlled up to 2.1 GHz by an electric field of 1.25 MV/cm. The large frequency tuning is attributed to the voltage-controlled magnetic anisotropy (VCMA) in a perpendicularly magnetized Ta/Pt/[Co/Ni]n/Co/AlOx structure. Moreover, the non-volatile VCMA effect enables cumulative control of the frequency using repetitive voltage pulses which mimic the potentiation and depression functions of biological synapses. Our results suggest that the voltage-driven frequency tuning of SHNOs facilitates the development of energy-efficient neuromorphic devices.
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Affiliation(s)
- Jong-Guk Choi
- Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Korea
| | | | - Min-Gu Kang
- Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Korea
| | - Doyoon Kim
- School of Electrical Engineering, Korea University, Seoul, 02841, Korea
| | - Jae-Sung Rieh
- School of Electrical Engineering, Korea University, Seoul, 02841, Korea
| | | | - Kab-Jin Kim
- Department of Physics, KAIST, Daejeon, 34141, Korea.
| | - Byong-Guk Park
- Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Korea.
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Kumar A, Rajabali M, González VH, Zahedinejad M, Houshang A, Åkerman J. Fabrication of voltage-gated spin Hall nano-oscillators. NANOSCALE 2022; 14:1432-1439. [PMID: 35018936 DOI: 10.1039/d1nr07505e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We demonstrate an optimized fabrication process for electric field (voltage gate) controlled nano-constriction spin Hall nano-oscillators (SHNOs), achieving feature sizes of <30 nm with easy to handle ma-N 2401 e-beam lithography negative tone resist. For the nanoscopic voltage gates, we utilize a two-step tilted ion beam etching approach and through-hole encapsulation using 30 nm HfOx. The optimized tilted etching process reduces sidewalls by 75% compared to no tilting. Moreover, the HfOx encapsulation avoids any sidewall shunting and improves gate breakdown. Our experimental results on W/CoFeB/MgO/SiO2 SHNOs show significant frequency tunability (6 MHz V-1) even for moderate perpendicular magnetic anisotropy. Circular patterns with diameter of 45 nm are achieved with an aspect ratio better than 0.85 for 80% of the population. The optimized fabrication process allows incorporating a large number of individual gates to interface to SHNO arrays for unconventional computing and densely packed spintronic neural networks.
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Affiliation(s)
- Akash Kumar
- Applied Spintronics Group, Department of Physics, University of Gothenburg, 412 96 Gothenburg, Sweden.
| | - Mona Rajabali
- Applied Spintronics Group, Department of Physics, University of Gothenburg, 412 96 Gothenburg, Sweden.
| | - Victor Hugo González
- Applied Spintronics Group, Department of Physics, University of Gothenburg, 412 96 Gothenburg, Sweden.
| | | | - Afshin Houshang
- Applied Spintronics Group, Department of Physics, University of Gothenburg, 412 96 Gothenburg, Sweden.
| | - Johan Åkerman
- Applied Spintronics Group, Department of Physics, University of Gothenburg, 412 96 Gothenburg, Sweden.
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Affiliation(s)
- Danijela Marković
- Unité Mixte de Physique CNRS, Thales, Université Paris-Saclay, Palaiseau, France.
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