Pub Date : 2024-06-03DOI: 10.1038/s44306-024-00014-7
Ding-Fu Shao, Evgeny Y. Tsymbal
Antiferromagnetic (AFM) spintronics has emerged as a subfield of spintronics, where an AFM Néel vector is used as a state variable. Efficient electric control and detection of the Néel vector are critical for spintronic applications. This review article features fundamental properties of AFM tunnel junctions (AFMTJs) as spintronic devices where such electric control and detection can be realized. We emphasize critical requirements for observing a large tunneling magnetoresistance (TMR) effect in AFMTJs with collinear and noncollinear AFM electrodes, such as a momentum-dependent spin polarization and Néel spin currents. We further discuss spin torques in AFMTJs that are capable of Néel vector switching. Overall, AFMTJs have potential to become a new standard for spintronics providing larger magnetoresistive effects, few orders of magnitude faster switching speed, and much higher packing density than conventional magnetic tunnel junctions (MTJs).
{"title":"Antiferromagnetic tunnel junctions for spintronics","authors":"Ding-Fu Shao, Evgeny Y. Tsymbal","doi":"10.1038/s44306-024-00014-7","DOIUrl":"10.1038/s44306-024-00014-7","url":null,"abstract":"Antiferromagnetic (AFM) spintronics has emerged as a subfield of spintronics, where an AFM Néel vector is used as a state variable. Efficient electric control and detection of the Néel vector are critical for spintronic applications. This review article features fundamental properties of AFM tunnel junctions (AFMTJs) as spintronic devices where such electric control and detection can be realized. We emphasize critical requirements for observing a large tunneling magnetoresistance (TMR) effect in AFMTJs with collinear and noncollinear AFM electrodes, such as a momentum-dependent spin polarization and Néel spin currents. We further discuss spin torques in AFMTJs that are capable of Néel vector switching. Overall, AFMTJs have potential to become a new standard for spintronics providing larger magnetoresistive effects, few orders of magnitude faster switching speed, and much higher packing density than conventional magnetic tunnel junctions (MTJs).","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00014-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141246216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The discovery of two-dimensional (2D) magnetism within atomically thin structures obtained from layered magnetic crystals has opened up a new realm for exploring magnetic heterostructures. This emerging field provides a foundational platform for investigating unique physical properties and exquisite phenomena at the nanometer and molecular/atomic scales. By engineering 2D interfaces using physical methods and selecting interlayer interactions, we can unlock the potential for extraordinary exchange dynamics, which extends to high-performance and high-density magnetic memory applications, as well as future advancements in neuromorphic and quantum computing. This review delves into recent advances in magnetic 2D materials, elucidates the mechanisms behind 2D interfaces, and highlights the development of 2D devices for spintronics and quantum information processing. Particular focus is placed on 2D magnetic heterostructures with topological properties, promising a resilient and low-error information system. Finally, we discuss the trends of 2D heterostructures for future electronics, considering the challenges and opportunities from physics, material synthesis, and technological perspectives.
{"title":"2D Magnetic heterostructures: spintronics and quantum future","authors":"Bingyu Zhang, Pengcheng Lu, Roozbeh Tabrizian, Philip X.-L. Feng, Yingying Wu","doi":"10.1038/s44306-024-00011-w","DOIUrl":"10.1038/s44306-024-00011-w","url":null,"abstract":"The discovery of two-dimensional (2D) magnetism within atomically thin structures obtained from layered magnetic crystals has opened up a new realm for exploring magnetic heterostructures. This emerging field provides a foundational platform for investigating unique physical properties and exquisite phenomena at the nanometer and molecular/atomic scales. By engineering 2D interfaces using physical methods and selecting interlayer interactions, we can unlock the potential for extraordinary exchange dynamics, which extends to high-performance and high-density magnetic memory applications, as well as future advancements in neuromorphic and quantum computing. This review delves into recent advances in magnetic 2D materials, elucidates the mechanisms behind 2D interfaces, and highlights the development of 2D devices for spintronics and quantum information processing. Particular focus is placed on 2D magnetic heterostructures with topological properties, promising a resilient and low-error information system. Finally, we discuss the trends of 2D heterostructures for future electronics, considering the challenges and opportunities from physics, material synthesis, and technological perspectives.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00011-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141182313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-09DOI: 10.1038/s44306-024-00015-6
Nihad Abuawwad, Manuel dos Santos Dias, Hazem Abusara, Samir Lounis
The emergence of topological magnetism in two-dimensional (2D) van der Waals (vdW) magnetic materials and their heterostructures is an essential ingredient for next-generation information technology devices. Here, we demonstrate the all-electric switching of the topological nature of individual magnetic objects emerging in 2D vdW heterobilayers. We show from the first principles that an external electric field modifies the vdW gap between CrTe2 and (Rh, Ti)Te2 layers and alters the underlying magnetic interactions. This enables switching between ferromagnetic skyrmions and meron pairs in the CrTe2/RhTe2 heterobilayer while it enhances the stability of frustrated antiferromagnetic merons in the CrTe2/TiTe2 heterobilayer. We envision that the electrical engineering of distinct topological magnetic solitons in a single device could pave the way for novel energy-efficient mechanisms to store and transmit information with applications in spintronics.
{"title":"Electrical engineering of topological magnetism in two-dimensional heterobilayers","authors":"Nihad Abuawwad, Manuel dos Santos Dias, Hazem Abusara, Samir Lounis","doi":"10.1038/s44306-024-00015-6","DOIUrl":"10.1038/s44306-024-00015-6","url":null,"abstract":"The emergence of topological magnetism in two-dimensional (2D) van der Waals (vdW) magnetic materials and their heterostructures is an essential ingredient for next-generation information technology devices. Here, we demonstrate the all-electric switching of the topological nature of individual magnetic objects emerging in 2D vdW heterobilayers. We show from the first principles that an external electric field modifies the vdW gap between CrTe2 and (Rh, Ti)Te2 layers and alters the underlying magnetic interactions. This enables switching between ferromagnetic skyrmions and meron pairs in the CrTe2/RhTe2 heterobilayer while it enhances the stability of frustrated antiferromagnetic merons in the CrTe2/TiTe2 heterobilayer. We envision that the electrical engineering of distinct topological magnetic solitons in a single device could pave the way for novel energy-efficient mechanisms to store and transmit information with applications in spintronics.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00015-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140895298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-03DOI: 10.1038/s44306-024-00012-9
Yuzan Xiong, Jayakrishnan M. P. Nair, Andrew Christy, James F. Cahoon, Amin Pishehvar, Xufeng Zhang, Benedetta Flebus, Wei Zhang
The opto-electronic oscillators (OEOs) hosting self-sustained oscillations by a time-delayed mechanism are of particular interest in long-haul signal transmission and processing. On the other hand, owing to their unique tunability and compatibility, magnons—as elementary excitations of spin waves—are advantageous carriers for coherent signal transduction across different platforms. In this work, we integrated an opto-electronic oscillator with a magnonic oscillator consisting of a microwave waveguide and a yttrium iron garnet sphere. We find that, in the presence of the magnetic sphere, the oscillator power spectrum exhibits sidebands flanking the fundamental OEO modes. The measured waveguide transmission reveals anti-crossing gaps, a hallmark of the coupling between the opto-electronic oscillator modes and the Walker modes of the sphere. Experimental results are well reproduced by a coupled-mode theory that accounts for nonlinear magnetostrictive interactions mediated by the magnetic sphere. Leveraging the advanced fiber-optic technologies in opto-electronics, this work lays out a new, hybrid platform for investigating long-distance coupling and nonlinearity in coherent magnonic phenomena.
{"title":"Magnon-photon coupling in an opto-electro-magnonic oscillator","authors":"Yuzan Xiong, Jayakrishnan M. P. Nair, Andrew Christy, James F. Cahoon, Amin Pishehvar, Xufeng Zhang, Benedetta Flebus, Wei Zhang","doi":"10.1038/s44306-024-00012-9","DOIUrl":"10.1038/s44306-024-00012-9","url":null,"abstract":"The opto-electronic oscillators (OEOs) hosting self-sustained oscillations by a time-delayed mechanism are of particular interest in long-haul signal transmission and processing. On the other hand, owing to their unique tunability and compatibility, magnons—as elementary excitations of spin waves—are advantageous carriers for coherent signal transduction across different platforms. In this work, we integrated an opto-electronic oscillator with a magnonic oscillator consisting of a microwave waveguide and a yttrium iron garnet sphere. We find that, in the presence of the magnetic sphere, the oscillator power spectrum exhibits sidebands flanking the fundamental OEO modes. The measured waveguide transmission reveals anti-crossing gaps, a hallmark of the coupling between the opto-electronic oscillator modes and the Walker modes of the sphere. Experimental results are well reproduced by a coupled-mode theory that accounts for nonlinear magnetostrictive interactions mediated by the magnetic sphere. Leveraging the advanced fiber-optic technologies in opto-electronics, this work lays out a new, hybrid platform for investigating long-distance coupling and nonlinearity in coherent magnonic phenomena.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00012-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140820730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-29DOI: 10.1038/s44306-024-00019-2
Christopher H. Marrows, Joseph Barker, Thomas A. Moore, Timothy Moorsom
Spintronics and magnetic materials exhibit many physical phenomena that are promising for implementing neuromorphic computing natively in hardware. Here, we review the current state-of-the-art, focusing on the areas of spintronic synapses, neurons, and neural networks. Many current implementations are based on the paradigm of reservoir computing, where the details of the network do not need to be known but where significant post-processing is needed. Benchmarks are given where possible. We discuss the scientific and technological advances needed to bring about spintronic neuromorphic computing that could be useful to an end-user in the medium term.
{"title":"Neuromorphic computing with spintronics","authors":"Christopher H. Marrows, Joseph Barker, Thomas A. Moore, Timothy Moorsom","doi":"10.1038/s44306-024-00019-2","DOIUrl":"10.1038/s44306-024-00019-2","url":null,"abstract":"Spintronics and magnetic materials exhibit many physical phenomena that are promising for implementing neuromorphic computing natively in hardware. Here, we review the current state-of-the-art, focusing on the areas of spintronic synapses, neurons, and neural networks. Many current implementations are based on the paradigm of reservoir computing, where the details of the network do not need to be known but where significant post-processing is needed. Benchmarks are given where possible. We discuss the scientific and technological advances needed to bring about spintronic neuromorphic computing that could be useful to an end-user in the medium term.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00019-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140808223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-25DOI: 10.1038/s44306-024-00010-x
Kyoung-Whan Kim, Byong-Guk Park, Kyung-Jin Lee
Spin torque is typically classified based on how the spin current is generated and injected into a magnet for manipulation. Spin-orbit torque arises from the spin-orbit interaction in a nearby normal metal, while spin-transfer torque results from exchange interactions in another ferromagnet. Recent studies have suggested that a ferromagnet itself can also generate a spin current through spin-orbit coupling, leading to the emergence of ferromagnet-induced spin-orbit torque as another class of spin torque. This novel torque mechanism not only inherits the advantages of spin-orbit torque architectures, such as separate reading and writing paths in memory applications but also offers the flexibility to control the generated spin direction by manipulating the orientation of the ferromagnet responsible for generating the spin current. In this article, we review the phenomena related to spin currents generated by ferromagnets, explore their physical descriptions in heterostructures, and discuss several spin torque architectures based on this effect. Ferromagnet-induced spin-orbit torque not only introduces new physical consequences by combining spin-orbit and exchange interactions but also offers a promising building block in spintronics with significant potential for diverse applications.
{"title":"Spin current and spin-orbit torque induced by ferromagnets","authors":"Kyoung-Whan Kim, Byong-Guk Park, Kyung-Jin Lee","doi":"10.1038/s44306-024-00010-x","DOIUrl":"10.1038/s44306-024-00010-x","url":null,"abstract":"Spin torque is typically classified based on how the spin current is generated and injected into a magnet for manipulation. Spin-orbit torque arises from the spin-orbit interaction in a nearby normal metal, while spin-transfer torque results from exchange interactions in another ferromagnet. Recent studies have suggested that a ferromagnet itself can also generate a spin current through spin-orbit coupling, leading to the emergence of ferromagnet-induced spin-orbit torque as another class of spin torque. This novel torque mechanism not only inherits the advantages of spin-orbit torque architectures, such as separate reading and writing paths in memory applications but also offers the flexibility to control the generated spin direction by manipulating the orientation of the ferromagnet responsible for generating the spin current. In this article, we review the phenomena related to spin currents generated by ferromagnets, explore their physical descriptions in heterostructures, and discuss several spin torque architectures based on this effect. Ferromagnet-induced spin-orbit torque not only introduces new physical consequences by combining spin-orbit and exchange interactions but also offers a promising building block in spintronics with significant potential for diverse applications.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00010-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140642061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-15DOI: 10.1038/s44306-023-00007-y
Daniel Staros, Brenda Rubenstein, Panchapakesan Ganesh
The ability to manipulate electronic spin channels in 2D materials is crucial for realizing next-generation spintronics. Spin filters are spintronic components that polarize spins using external electromagnetic fields or intrinsic material properties like magnetism. Recently, topological protection from backscattering has emerged as an enticing feature that can be leveraged to enhance the robustness of 2D spin filters. In this work, we propose and then characterize one of the first 2D topological spin filters: bilayer CrI3/1T’-WTe2. To do so, we use a combination of density functional theory, maximally localized Wannier functions, and quantum transport calculations to demonstrate that a terraced bilayer satisfies the principal criteria for being a topological spin filter: namely, that it is gapless, exhibits spin-polarized charge transfer from WTe2 to CrI3 that renders the bilayer metallic, and has a topological boundary which retains the edge conductance of monolayer 1T’-WTe2. In particular, we observe that small negative ferromagnetic moments are induced on the W atoms in the bilayer, and the atomic magnetic moments on the Cr are approximately 3.2 μB/Cr compared to 2.9 μB/Cr in freestanding monolayer CrI3. Subtracting the charge and spin densities of the constituent monolayers from those of the bilayer further reveals spin-orbit coupling-enhanced spin-polarized charge transfer from WTe2 to CrI3. We demonstrate that the bilayer is topologically trivial by showing that its Chern number is zero. Lastly, we show that interfacial scattering at the boundary between the terraced materials does not remove WTe2’s edge conductance. Altogether, this evidence indicates that BL 1T’-WTe2/CrI3 is gapless, magnetic, and topologically trivial, meaning that a terraced WTe2/CrI3 bilayer heterostructure in which only a portion of a WTe2 monolayer is topped with CrI3 is a promising candidate for a 2D topological spin filter. Our results further suggest that 1D chiral edge states may be realized by stacking strongly ferromagnetic monolayers, like CrI3, atop 2D nonmagnetic Weyl semimetals like 1T’-WTe2.
{"title":"A first-principles study of bilayer 1T''-WTe2/CrI3: a candidate topological spin filter","authors":"Daniel Staros, Brenda Rubenstein, Panchapakesan Ganesh","doi":"10.1038/s44306-023-00007-y","DOIUrl":"10.1038/s44306-023-00007-y","url":null,"abstract":"The ability to manipulate electronic spin channels in 2D materials is crucial for realizing next-generation spintronics. Spin filters are spintronic components that polarize spins using external electromagnetic fields or intrinsic material properties like magnetism. Recently, topological protection from backscattering has emerged as an enticing feature that can be leveraged to enhance the robustness of 2D spin filters. In this work, we propose and then characterize one of the first 2D topological spin filters: bilayer CrI3/1T’-WTe2. To do so, we use a combination of density functional theory, maximally localized Wannier functions, and quantum transport calculations to demonstrate that a terraced bilayer satisfies the principal criteria for being a topological spin filter: namely, that it is gapless, exhibits spin-polarized charge transfer from WTe2 to CrI3 that renders the bilayer metallic, and has a topological boundary which retains the edge conductance of monolayer 1T’-WTe2. In particular, we observe that small negative ferromagnetic moments are induced on the W atoms in the bilayer, and the atomic magnetic moments on the Cr are approximately 3.2 μB/Cr compared to 2.9 μB/Cr in freestanding monolayer CrI3. Subtracting the charge and spin densities of the constituent monolayers from those of the bilayer further reveals spin-orbit coupling-enhanced spin-polarized charge transfer from WTe2 to CrI3. We demonstrate that the bilayer is topologically trivial by showing that its Chern number is zero. Lastly, we show that interfacial scattering at the boundary between the terraced materials does not remove WTe2’s edge conductance. Altogether, this evidence indicates that BL 1T’-WTe2/CrI3 is gapless, magnetic, and topologically trivial, meaning that a terraced WTe2/CrI3 bilayer heterostructure in which only a portion of a WTe2 monolayer is topped with CrI3 is a promising candidate for a 2D topological spin filter. Our results further suggest that 1D chiral edge states may be realized by stacking strongly ferromagnetic monolayers, like CrI3, atop 2D nonmagnetic Weyl semimetals like 1T’-WTe2.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-023-00007-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140553062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-05DOI: 10.1038/s44306-024-00009-4
Jingjing Lu, Yan Xu, Jingsong Cui, Peng Zhang, Chenxi Zhou, Hanuman Singh, Shuai Zhang, Long You, Jeongmin Hong
Two-dimensional semiconductors, including transition metal dichalcogenides (TMDs), are of interest in electronics and photonics but remain nonmagnetic in their intrinsic form. Atomic modulation using physical and chemical ways is an effective means to control the physical properties such as magnetic and electrical properties of two-dimensional materials which can be controlled by irradiation. Here we treat mechanically exfoliated MoS2 with a helium ion beam, which exhibits semiconducting and ferromagnetic ordering at room temperature, while Monte Carlo simulations and theoretical calculations confirmed that the control of nanoholes result in the presence of magnetism. In addition, the irradiation results of multilayer MoS2 show that the magnetic moment increases with the increase of 10 layers. The conductivity remains virtually unchanged before and after being treated by a helium ion beam. The treated MoS2 spintronic device displays the switch of ‘on/off” under the light, magnetic field, and/or electric field, which means 2D photosensitive ferromagnetic semiconductor functions are successfully demonstrated at room temperature.
{"title":"Room temperature photosensitive ferromagnetic semiconductor using MoS2","authors":"Jingjing Lu, Yan Xu, Jingsong Cui, Peng Zhang, Chenxi Zhou, Hanuman Singh, Shuai Zhang, Long You, Jeongmin Hong","doi":"10.1038/s44306-024-00009-4","DOIUrl":"10.1038/s44306-024-00009-4","url":null,"abstract":"Two-dimensional semiconductors, including transition metal dichalcogenides (TMDs), are of interest in electronics and photonics but remain nonmagnetic in their intrinsic form. Atomic modulation using physical and chemical ways is an effective means to control the physical properties such as magnetic and electrical properties of two-dimensional materials which can be controlled by irradiation. Here we treat mechanically exfoliated MoS2 with a helium ion beam, which exhibits semiconducting and ferromagnetic ordering at room temperature, while Monte Carlo simulations and theoretical calculations confirmed that the control of nanoholes result in the presence of magnetism. In addition, the irradiation results of multilayer MoS2 show that the magnetic moment increases with the increase of 10 layers. The conductivity remains virtually unchanged before and after being treated by a helium ion beam. The treated MoS2 spintronic device displays the switch of ‘on/off” under the light, magnetic field, and/or electric field, which means 2D photosensitive ferromagnetic semiconductor functions are successfully demonstrated at room temperature.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00009-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140348871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Topologically protected spin textures, such as magnetic skyrmions, have shown the potential for high-density data storage and energy-efficient computing applications owing to their particle-like behavior, small size, and low driving current requirements. Evaluating the writing and reading of the skyrmion’s magnetic and electrical characteristics is crucial to implementing these devices. In this paper, we present the magnetic heterostructure Hall bar device and study the anomalous Hall and topological Hall signals in these devices. Using different measurement techniques, we investigate the magnetic and electrical characteristics of the magnetic structure. We measure the skyrmion topological resistivity and the magnetic field at different temperatures. MFM imaging and micromagnetic simulations further explain the anomalous Hall and topological Hall resistivity characteristics at various magnetic fields and temperatures. The study is extended to propose a skyrmion-based synaptic device showing spin-orbit torque-controlled plasticity. The resistance states are read using the anomalous Hall measurement technique. The device integration in a neuromorphic circuit is simulated in a 3-layer feedforward artificial neural network ANN. Based on the proposed synapses, the neural network is trained and tested on the MNIST data set, where a recognition accuracy performance of about 90% is achieved. Considering the nanosecond reading/writing time scale and a good system level performance, these devices exhibit a substantial prospect for energy-efficient neuromorphic computing.
{"title":"Anomalous hall and skyrmion topological hall resistivity in magnetic heterostructures for the neuromorphic computing applications","authors":"Aijaz H. Lone, Xuecui Zou, Debasis Das, Xuanyao Fong, Gianluca Setti, Hossein Fariborzi","doi":"10.1038/s44306-023-00006-z","DOIUrl":"10.1038/s44306-023-00006-z","url":null,"abstract":"Topologically protected spin textures, such as magnetic skyrmions, have shown the potential for high-density data storage and energy-efficient computing applications owing to their particle-like behavior, small size, and low driving current requirements. Evaluating the writing and reading of the skyrmion’s magnetic and electrical characteristics is crucial to implementing these devices. In this paper, we present the magnetic heterostructure Hall bar device and study the anomalous Hall and topological Hall signals in these devices. Using different measurement techniques, we investigate the magnetic and electrical characteristics of the magnetic structure. We measure the skyrmion topological resistivity and the magnetic field at different temperatures. MFM imaging and micromagnetic simulations further explain the anomalous Hall and topological Hall resistivity characteristics at various magnetic fields and temperatures. The study is extended to propose a skyrmion-based synaptic device showing spin-orbit torque-controlled plasticity. The resistance states are read using the anomalous Hall measurement technique. The device integration in a neuromorphic circuit is simulated in a 3-layer feedforward artificial neural network ANN. Based on the proposed synapses, the neural network is trained and tested on the MNIST data set, where a recognition accuracy performance of about 90% is achieved. Considering the nanosecond reading/writing time scale and a good system level performance, these devices exhibit a substantial prospect for energy-efficient neuromorphic computing.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-023-00006-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140104567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Physical implementation of neuromorphic computing using spintronics technology has attracted recent attention for the future energy-efficient AI at nanoscales. Reservoir computing (RC) is promising for realizing the neuromorphic computing device. By memorizing past input information and its nonlinear transformation, RC can handle sequential data and perform time-series forecasting and speech recognition. However, the current performance of spintronics RC is poor due to the lack of understanding of its mechanism. Here we demonstrate that nanoscale physical RC using propagating spin waves can achieve high computational power comparable with other state-of-art systems. We develop the theory with response functions to understand the mechanism of high performance. The theory clarifies that wave-based RC generates Volterra series of the input through delayed and nonlinear responses. The delay originates from wave propagation. We find that the scaling of system sizes with the propagation speed of spin waves plays a crucial role in achieving high performance.
{"title":"Universal scaling between wave speed and size enables nanoscale high-performance reservoir computing based on propagating spin-waves","authors":"Satoshi Iihama, Yuya Koike, Shigemi Mizukami, Natsuhiko Yoshinaga","doi":"10.1038/s44306-024-00008-5","DOIUrl":"10.1038/s44306-024-00008-5","url":null,"abstract":"Physical implementation of neuromorphic computing using spintronics technology has attracted recent attention for the future energy-efficient AI at nanoscales. Reservoir computing (RC) is promising for realizing the neuromorphic computing device. By memorizing past input information and its nonlinear transformation, RC can handle sequential data and perform time-series forecasting and speech recognition. However, the current performance of spintronics RC is poor due to the lack of understanding of its mechanism. Here we demonstrate that nanoscale physical RC using propagating spin waves can achieve high computational power comparable with other state-of-art systems. We develop the theory with response functions to understand the mechanism of high performance. The theory clarifies that wave-based RC generates Volterra series of the input through delayed and nonlinear responses. The delay originates from wave propagation. We find that the scaling of system sizes with the propagation speed of spin waves plays a crucial role in achieving high performance.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00008-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140000831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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