1
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Camarasa-Gómez M, Hernangómez-Pérez D, Evers F. Spin-Orbit Torque in Single-Molecule Junctions from ab Initio. J Phys Chem Lett 2024; 15:5747-5753. [PMID: 38775633 PMCID: PMC11145651 DOI: 10.1021/acs.jpclett.4c00502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 05/11/2024] [Accepted: 05/14/2024] [Indexed: 05/31/2024]
Abstract
The use of electric fields applied across magnetic heterojunctions that lack spatial inversion symmetry has been previously proposed as a nonmagnetic means of controlling localized magnetic moments through spin-orbit torques (SOT). The implementation of this concept at the single-molecule level has remained a challenge, however. Here, we present first-principles calculations of SOT in a single-molecule junction under bias and beyond linear response. Employing a self-consistency scheme invoking density functional theory and nonequilibrium Green's function theory including spin-orbit interaction, we compute the change of the magnetization with the bias voltage and the associated current-induced SOT. Within the linear regime our quantitative estimates for the SOT in single-molecule junctions yield values similar to those known for magnetic interfaces. Our findings contribute to an improved microscopic understanding of SOT in single molecules.
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Affiliation(s)
- María Camarasa-Gómez
- Institute
of Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
- Department
of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Daniel Hernangómez-Pérez
- Institute
of Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
- CIC
nanoGUNE BRTA, Tolosa Hiribidea 76, 20018 San Sebastián, Spain
| | - Ferdinand Evers
- Institute
of Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
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2
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Du Y, Zhao Y, Wang L, He Z, Wu Y, Wang C, Zhao L, Jiang Z, Liu M, Zhou Z. Deterministic Magnetization Reversal in Synthetic Antiferromagnets using Natural Light. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2302884. [PMID: 37403297 DOI: 10.1002/smll.202302884] [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: 04/06/2023] [Revised: 05/31/2023] [Indexed: 07/06/2023]
Abstract
Traditional current-driven spintronics is limited by localized heating issues and large energy consumption, restricting their data storage density and operation speed. Meanwhile, voltage-driven spintronics with much lower energy dissipation also suffers from charge-induced interfacial corrosion. Thereby finding a novel way of tuning ferromagnetism is crucial for spintronics with energy-saving and good reliability. Here, a visible light tuning of interfacial exchange interaction via photoelectron doping into synthetic antiferromagnetic heterostructure of CoFeB/Cu/CoFeB/PN Si substrate is demonstrated. Then, a complete, reversible magnetism switching between antiferromagnetic (AFM) and ferromagnetic (FM) states with visible light on and off is realized. Moreover, a visible light control of 180° deterministic magnetization switching with a tiny magnetic bias field is achieved. The magnetic optical Kerr effect results further reveal the magnetic domain switching pathway between AFM and FM domains. The first-principle calculations conclude that the photoelectrons fill in the unoccupied band and raise the Fermi energy, which increases the exchange interaction. Lastly, a prototype device with visible light control of two states switching with a 0.35% giant magnetoresistance ratio change (maximal 0.4%), paving the way toward fast, compact, and energy-efficient solar-driven memories is fabricated.
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Affiliation(s)
- Yujing Du
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, State Key Laboratory for Manufacturing Systems Engineering, The International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Yifan Zhao
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, State Key Laboratory for Manufacturing Systems Engineering, The International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Lei Wang
- Center for Spintronics and Quantum Systems, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, No. 28 Xianning West Road Xi'an, Shaanxi, 710049, China
| | - Zhexi He
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, State Key Laboratory for Manufacturing Systems Engineering, The International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Yangyang Wu
- School of Mathematical Sciences, Tiangong University, Tianjin, 300387, China
| | - Chenying Wang
- State Key Laboratory for Manufacturing Systems Engineering, Collaborative Innovation Center of High-End Manufacturing Equipment, The International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Libo Zhao
- State Key Laboratory for Manufacturing Systems Engineering, Collaborative Innovation Center of High-End Manufacturing Equipment, The International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Zhuangde Jiang
- State Key Laboratory for Manufacturing Systems Engineering, Collaborative Innovation Center of High-End Manufacturing Equipment, The International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Ming Liu
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, State Key Laboratory for Manufacturing Systems Engineering, The International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Ziyao Zhou
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, State Key Laboratory for Manufacturing Systems Engineering, The International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technology, Xi'an Jiaotong University, Xi'an, 710049, China
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3
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Madadi Asl M, Ramezani Akbarabadi S. Voltage-dependent plasticity of spin-polarized conductance in phenyl-based single-molecule magnetic tunnel junctions. PLoS One 2021; 16:e0257228. [PMID: 34506579 PMCID: PMC8432808 DOI: 10.1371/journal.pone.0257228] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/27/2021] [Indexed: 11/24/2022] Open
Abstract
Synaptic strengths between neurons in brain networks are highly adaptive due to synaptic plasticity. Spike-timing-dependent plasticity (STDP) is a form of synaptic plasticity induced by temporal correlations between the firing activity of neurons. The development of experimental techniques in recent years enabled the realization of brain-inspired neuromorphic devices. Particularly, magnetic tunnel junctions (MTJs) provide a suitable means for the implementation of learning processes in molecular junctions. Here, we first considered a two-neuron motif subjected to STDP. By employing theoretical analysis and computer simulations we showed that the dynamics and emergent structure of the motif can be predicted by introducing an effective two-neuron synaptic conductance. Then, we considered a phenyl-based single-molecule MTJ connected to two ferromagnetic (FM) cobalt electrodes and investigated its electrical properties using the non-equilibrium Green’s function (NEGF) formalism. Similar to the two-neuron motif, we introduced an effective spin-polarized conductance in the MTJ. Depending on the polarity, frequency and strength of the bias voltage applied to the MTJ, the system can learn input signals by adaptive changes of the effective conductance. Interestingly, this voltage-dependent plasticity is an intrinsic property of the MTJ where its behavior is reminiscent of the classical temporally asymmetric STDP. Furthermore, the shape of voltage-dependent plasticity in the MTJ is determined by the molecule-electrode coupling strength or the length of the molecule. Our results may be relevant for the development of single-molecule devices that capture the adaptive properties of synapses in the brain.
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Affiliation(s)
- Mojtaba Madadi Asl
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
- * E-mail:
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4
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Yu J, Bang D, Mishra R, Ramaswamy R, Oh JH, Park HJ, Jeong Y, Van Thach P, Lee DK, Go G, Lee SW, Wang Y, Shi S, Qiu X, Awano H, Lee KJ, Yang H. Long spin coherence length and bulk-like spin-orbit torque in ferrimagnetic multilayers. NATURE MATERIALS 2019; 18:29-34. [PMID: 30510269 DOI: 10.1038/s41563-018-0236-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/23/2018] [Indexed: 06/09/2023]
Abstract
Spintronics relies on magnetization switching through current-induced spin torques. However, because spin transfer torque for ferromagnets is a surface torque, a large switching current is required for a thick, thermally stable ferromagnetic cell, and this remains a fundamental obstacle for high-density non-volatile applications with ferromagnets. Here, we report a long spin coherence length and associated bulk-like torque characteristics in an antiferromagnetically coupled ferrimagnetic multilayer. We find that a transverse spin current can pass through >10-nm-thick ferrimagnetic Co/Tb multilayers, whereas it is entirely absorbed by a 1-nm-thick ferromagnetic Co/Ni multilayer. We also find that the switching efficiency of Co/Tb multilayers partially reflects a bulk-like torque characteristic, as it increases with ferrimagnet thickness up to 8 nm and then decreases, in clear contrast to the 1/thickness dependence of ferromagnetic Co/Ni multilayers. Our results on antiferromagnetically coupled systems will invigorate research towards the development of energy-efficient spintronics.
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Affiliation(s)
- Jiawei Yu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Do Bang
- Toyota Technological Institute, Tempaku, Nagoya, Japan
- Institute of Materials Science, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Rahul Mishra
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Rajagopalan Ramaswamy
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Jung Hyun Oh
- Department of Materials Science and Engineering, Korea University, Seoul, Korea
| | - Hyeon-Jong Park
- KU-KIST Graduate School of Conversing Science and Technology, Korea University, Seoul, Korea
| | - Yunboo Jeong
- Department of Semiconductor Systems Engineering, Korea University, Seoul, Korea
| | - Pham Van Thach
- Toyota Technological Institute, Tempaku, Nagoya, Japan
- Institute of Materials Science, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Dong-Kyu Lee
- Department of Materials Science and Engineering, Korea University, Seoul, Korea
| | - Gyungchoon Go
- Department of Materials Science and Engineering, Korea University, Seoul, Korea
| | - Seo-Won Lee
- Department of Materials Science and Engineering, Korea University, Seoul, Korea
| | - Yi Wang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Shuyuan Shi
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Xuepeng Qiu
- Shanghai Key Laboratory of Special Artificial Macrostructure Materials and Technology and School of Physics Science and Engineering, Tongji University, Shanghai, China
| | | | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul, Korea.
- KU-KIST Graduate School of Conversing Science and Technology, Korea University, Seoul, Korea.
- Department of Semiconductor Systems Engineering, Korea University, Seoul, Korea.
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
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5
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Kaiju H, Misawa T, Nagahama T, Komine T, Kitakami O, Fujioka M, Nishii J, Xiao G. Robustness of Voltage-induced Magnetocapacitance. Sci Rep 2018; 8:14709. [PMID: 30279552 PMCID: PMC6168469 DOI: 10.1038/s41598-018-33065-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 09/18/2018] [Indexed: 11/09/2022] Open
Abstract
One of the most important achievements in the field of spintronics is the development of magnetic tunnel junctions (MTJs). MTJs exhibit a large tunneling magnetoresistance (TMR). However, TMR is strongly dependent on biasing voltage, generally, decreasing with applying bias. The rapid decay of TMR was a major deficiency of MTJs. Here we report a new phenomenon at room temperature, in which the tunneling magnetocapacitance (TMC) increases with biasing voltage in an MTJ system based on Co40Fe40B20/MgO/Co40Fe40B20. We have observed a maximum TMC value of 102% under appropriate biasing, which is the largest voltage-induced TMC effect ever reported for MTJs. We have found excellent agreement between theory and experiment for the bipolar biasing regions using Debye-Fröhlich model combined with quartic barrier approximation and spin-dependent drift-diffusion model. Based on our calculation, we predict that the voltage-induced TMC ratio could reach 1100% in MTJs with a corresponding TMR value of 604%. Our work has provided a new understanding on the voltage-induced AC spin-dependent transport in MTJs. The results reported here may open a novel pathway for spintronics applications, e.g., non-volatile memories and spin logic circuits.
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Affiliation(s)
- Hideo Kaiju
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, 001-0020, Japan.
| | - Takahiro Misawa
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, 001-0020, Japan
| | - Taro Nagahama
- Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Takashi Komine
- Graduate School of Science and Engineering, Ibaraki University, Hitachi, Ibaraki, 316-8511, Japan
| | - Osamu Kitakami
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, 980-8577, Japan
| | - Masaya Fujioka
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, 001-0020, Japan
| | - Junji Nishii
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, 001-0020, Japan
| | - Gang Xiao
- Department of Physics, Brown University, Providence, RI, 02912, USA
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6
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Banuazizi SAH, Åkerman J. Microwave probe stations with three-dimensional control of the magnetic field to study high-frequency dynamics in nanoscale devices. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:064701. [PMID: 29960541 DOI: 10.1063/1.5032219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present two microwave probe stations with motorized rotary stages for adjusting the magnitude and angle of the applied magnetic field. In the first system, the magnetic field is provided by an electromagnet and can be adjusted from 0 to ∼1.4 T while its polar angle (θ) can be varied from 0° to 360°. In the second system, the magnetic field is provided by a Halbach array permanent magnet, which can be rotated and translated to cover the full range of polar (θ) and azimuthal (φ) angles with a tunable field magnitude up to ∼1 T. Both systems are equipped with microwave probes, bias-Ts, amplifiers, and spectrum analyzers to allow for microwave characterization up to 40 GHz, as well as software to automatically perform continuous large sets of electrical and microwave measurements.
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Affiliation(s)
- Seyed Amir Hossein Banuazizi
- Materials and Nanophysics, Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista, Sweden
| | - Johan Åkerman
- Materials and Nanophysics, Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista, Sweden
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7
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Moriyama T, Kamiya M, Oda K, Tanaka K, Kim KJ, Ono T. Magnetic Moment Orientation-Dependent Spin Dissipation in Antiferromagnets. PHYSICAL REVIEW LETTERS 2017; 119:267204. [PMID: 29328700 DOI: 10.1103/physrevlett.119.267204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Indexed: 06/07/2023]
Abstract
Spin interaction in antiferromagnetic materials is of central interest in the recently emerging antiferromagnetic spintronics. In this Letter, we explore the spin current interaction in antiferromagnetic FeMn by the spin pumping effect. Exchange biased FeNi/FeMn films, in which the Néel vector can be presumably controlled via the exchange spring effect, are employed to investigate the damping enhancement depending on the relative orientation between the Néel vector and the polarization of the pumped spin current. The correlation between the enhanced damping and the strength of the exchange bias suggests that the twisting of the Néel vector induces an additional spin dissipation, which verifies that the Slonczewski-type spin torque is effective even in antiferromagnetic materials.
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Affiliation(s)
- Takahiro Moriyama
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Michinari Kamiya
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Kent Oda
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Kensho Tanaka
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Kab-Jin Kim
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Teruo Ono
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
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8
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Li ZD, Li QY, Xu TF, He PB. Breathers and rogue waves excited by all-magnonic spin-transfer torque. Phys Rev E 2016; 94:042220. [PMID: 27841617 DOI: 10.1103/physreve.94.042220] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Indexed: 11/07/2022]
Abstract
In terms of Darboux transformation we investigate the dynamic process of spin wave passing through a magnetic soliton. It causes nonlinear excitations, such as Akhmediev breathers solution and Kuznetsov-Ma soliton. The former case demonstrates a spatial periodic process of a magnetic soliton forming the petal with four pieces. The spatial separation of adjacent magnetic petals increases rapidly, while one valley splits into two and the amplitude of valley increases gradually with the increasing amplitude of spin wave. The other case shows a localized process of the spin-wave background. In the limit case, we get rogue waves and clarify its formation mechanism.
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Affiliation(s)
- Zai-Dong Li
- Department of Applied Physics, Hebei University of Technology, Tianjin 300401, China.,International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Qiu-Yan Li
- Department of Applied Physics, Hebei University of Technology, Tianjin 300401, China
| | - Tian-Fu Xu
- Department of Physics, Yanshan University, Qinhuangdao 066004, China
| | - Peng-Bin He
- School of Physics and Electronics, Hunan University, Changsha 410082, China
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9
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Abstract
The use of spin transfer nano-oscillators (STNOs) to generate microwave signals in nanoscale devices has aroused tremendous and continuous research interest in recent years. Their key features are frequency tunability, nanoscale size, broad working temperature, and easy integration with standard silicon technology. In this feature article, we give an overview of recent developments and breakthroughs in the materials, geometry design and properties of STNOs. We focus in more depth on our latest advances in STNOs with perpendicular anisotropy, showing a way to improve the output power of STNO towards the μW range. Challenges and perspectives of the STNOs that might be productive topics for future research are also briefly discussed.
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Affiliation(s)
- Zhongming Zeng
- Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, Suzhou 215123, P. R. China.
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10
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Kim J, Sinha J, Hayashi M, Yamanouchi M, Fukami S, Suzuki T, Mitani S, Ohno H. Layer thickness dependence of the current-induced effective field vector in Ta|CoFeB|MgO. NATURE MATERIALS 2013; 12:240-5. [PMID: 23263641 DOI: 10.1038/nmat3522] [Citation(s) in RCA: 167] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 11/13/2012] [Indexed: 05/17/2023]
Abstract
Current-induced effective magnetic fields can provide efficient ways of electrically manipulating the magnetization of ultrathin magnetic heterostructures. Two effects, known as the Rashba spin orbit field and the spin Hall spin torque, have been reported to be responsible for the generation of the effective field. However, a quantitative understanding of the effective field, including its direction with respect to the current flow, is lacking. Here we describe vector measurements of the current-induced effective field in Ta|CoFeB|MgO heterostructrures. The effective field exhibits a significant dependence on the Ta and CoFeB layer thicknesses. In particular, a 1 nm thickness variation of the Ta layer can change the magnitude of the effective field by nearly two orders of magnitude. Moreover, its sign changes when the Ta layer thickness is reduced, indicating that there are two competing effects contributing to it. Our results illustrate that the presence of atomically thin metals can profoundly change the landscape for controlling magnetic moments in magnetic heterostructures electrically.
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Affiliation(s)
- Junyeon Kim
- National Institute for Materials Science, Tsukuba 305-0047, Japan
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11
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Li LJ, Zhu B, Ding SJ, Lu HL, Sun QQ, Jiang A, Zhang DW, Zhu C. Three-dimensional AlZnO/Al2O3/AlZnO nanocapacitor arrays on Si substrate for energy storage. NANOSCALE RESEARCH LETTERS 2012; 7:544. [PMID: 23031347 PMCID: PMC3547769 DOI: 10.1186/1556-276x-7-544] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 09/24/2012] [Indexed: 05/31/2023]
Abstract
High density three-dimensional AZO/Al2O3/AZO nanocapacitor arrays have been fabricated for energy storage applications. Using atomic layer deposition technique, the stack of AZO/Al2O3/AZO has been grown in the porous anodic alumina template which is directly formed on the Si substrate. The fabricated capacitor shows a high capacitance density of 15.3 fF/μm2 at 100 kHz, which is nearly 2.5 times over the planar capacitor under identical conditions in theory. Further, the charge-discharge characteristics of the capacitor are characterized, indicating that the resistance-capacitance time constants are equal to 300 ns for the charging and discharging processes, and have no dependence on the voltage supply. This reflects good power characteristics of the electrostatic capacitor.
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Affiliation(s)
- Lian-Jie Li
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Bao Zhu
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Shi-Jin Ding
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Hong-Liang Lu
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Qing-Qing Sun
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Anquan Jiang
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - David Wei Zhang
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Chunxiang Zhu
- Silicon Nano Device Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore 119260, Singapore
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12
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Ghosh A, Auffret S, Ebels U, Bailey WE. Penetration depth of transverse spin current in ultrathin ferromagnets. PHYSICAL REVIEW LETTERS 2012; 109:127202. [PMID: 23005979 DOI: 10.1103/physrevlett.109.127202] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Indexed: 06/01/2023]
Abstract
We report a novel depth dependence for the penetration of spin current into ultrathin ferromagnets. Ferromagnetic resonance measurements show that transverse spin current pumped into three structurally distinct ferromagnets is attenuated, on reflection, by an amount proportional to the ferromagnetic layer thickness, saturating abruptly at 1.2 ± 0.1 nm. The observed power-law decay, differing significantly from the (exponential) characteristic-length dependence for longitudinal spin current, confirms models of spin momentum transfer which have been inaccessible to experiment.
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Affiliation(s)
- A Ghosh
- SPINTEC, UMR CEA/CNRS/UJF/Grenoble INP, INAC, France
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13
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Otani Y, Kimura T. Manipulation of spin currents in metallic systems. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:3136-3149. [PMID: 21727118 DOI: 10.1098/rsta.2011.0010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The transport properties of diffusive spin currents have been investigated in lateral ferromagnetic/non-magnetic metal hybrid structures. The spin diffusion processes were found to be strongly dependent on the magnitude of the spin resistances of connected materials. Efficient spin injection and detection are accomplished by optimizing the junction structures on the basis of the spin resistance circuitry. The magnetization switching of a nanoscale ferromagnetic particle and also room temperature spin Hall effect measurements were realized by using an efficient pure-spin-current injection.
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Affiliation(s)
- Yoshichika Otani
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
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14
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Zayets V, Saito H, Yuasa S, Ando K. Magnetization-dependent loss in an (Al,Ga)As optical waveguide with an embedded Fe micromagnet. OPTICS LETTERS 2010; 35:931-933. [PMID: 20364173 DOI: 10.1364/ol.35.000931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The dependence of waveguiding loss on the magnetization of a Fe micromagnet embedded into the (Al,Ga)As optical waveguide was examined as a possible readout method for the spin-photon memory. The optical detection of the magnetization direction of a Fe micromagnet was demonstrated for the micromagnet sizes of 3 microm x 4 microm and 3 microm x 8 microm with signal-to-noise ratios of 4.8 and 6 dB, respectively. In the case of smaller sizes, the use of spin injection from the micromagnet into a semiconductor optical amplifier was proposed for the optical detection of the magnetization.
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Affiliation(s)
- V Zayets
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Umezono 1-1-4, Tsukuba, Ibaraki 305-8568, Japan.
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15
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Yanson IK, Fisun VV, Naidyuk YG, Balkashin OP, Triputen LY, Konovalenko A, Korenivski V. Current driven tri-stable resistance states in magnetic point contacts. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:355004. [PMID: 21828625 DOI: 10.1088/0953-8984/21/35/355004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Point contacts between normal and ferromagnetic metals are investigated using magnetoresistance and transport spectroscopy measurements combined with micromagnetic simulations. Pronounced hysteresis in the point contact resistance versus both bias current and external magnetic field are observed. It is found that such hysteretic resistance can exhibit, in addition to bi-stable resistance states found in ordinary spin valves, tri-stable resistance states with a middle resistance level. We interpret these observations in terms of surface spin valve and spin vortex states, originating from a substantially modified spin structure at the ferromagnetic interface in the contact core. We argue that these surface spin states, subject to a weakened exchange interaction, dominate the effects of spin transfer torques on the nanometer scale.
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Affiliation(s)
- I K Yanson
- B Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 47 Lenin Avenue, 61103, Kharkiv, Ukraine
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16
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Haney PM, MacDonald AH. Current-induced torques due to compensated antiferromagnets. PHYSICAL REVIEW LETTERS 2008; 100:196801. [PMID: 18518471 DOI: 10.1103/physrevlett.100.196801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Indexed: 05/26/2023]
Abstract
We analyze the influence of current-induced torques on the magnetization configuration of a ferromagnet in a circuit containing a compensated antiferromagnet. We argue that these torques are generically nonzero and determine their form by considering spin-dependent scattering at a compensated antiferromagnetic interface. Because of symmetry dictated differences in the form of the current-induced torque, the phase diagram which expresses the dependence of the ferromagnetic configuration on the current and external magnetic field differs qualitatively from its ferromagnet-only counterpart.
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Affiliation(s)
- Paul M Haney
- Department of Physics, The University of Texas at Austin, Austin, TX 78712-0264, USA
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17
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Morrow P, Tang XT, Parker TC, Shima M, Wang GC. Magnetoresistance of oblique angle deposited multilayered Co/Cu nanocolumns measured by a scanning tunnelling microscope. NANOTECHNOLOGY 2008; 19:065712. [PMID: 21730718 DOI: 10.1088/0957-4484/19/6/065712] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this work we present the first magnetoresistance measurements on multilayered vertical Co(∼6 nm)/Cu(∼6 nm) and slanted Co(x nm)/Cu(x nm) (with x≈6, 11, and 16 nm) nanocolumns grown by oblique angle vapour deposition. The measurements are performed at room temperature on the as-deposited nanocolumn samples using a scanning tunnelling microscope to establish electronic contact with a small number of nanocolumns while an electromagnet generates a time varying (0.1 Hz) magnetic field in the plane of the substrate. The samples show a giant magnetoresistance (GMR) response ranging from 0.2 to 2%, with the higher GMR values observed for the thinner layers. For the slanted nanocolumns, we observed anisotropy in the GMR with respect to the relative orientation (parallel or perpendicular) between the incident vapour flux and the magnetic field applied in the substrate plane. We explain the anisotropy by noting that the column axis is the magnetic easy axis, so the magnetization reversal occurs more easily when the magnetic field is applied along the incident flux direction (i.e., nearly along the column axis) than when the field is applied perpendicular to the incident flux direction.
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Affiliation(s)
- P Morrow
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, NY 12180-3590, USA
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18
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Krause S, Berbil-Bautista L, Herzog G, Bode M, Wiesendanger R. Current-induced magnetization switching with a spin-polarized scanning tunneling microscope. Science 2007; 317:1537-40. [PMID: 17872442 DOI: 10.1126/science.1145336] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Switching the magnetization of a magnetic bit by injection of a spin-polarized current offers the possibility for the development of innovative high-density data storage technologies. We show how individual superparamagnetic iron nanoislands with typical sizes of 100 atoms can be addressed and locally switched using a magnetic scanning probe tip, thus demonstrating current-induced magnetization reversal across a vacuum barrier combined with the ultimate resolution of spin-polarized scanning tunneling microscopy. Our technique allows us to separate and quantify three fundamental contributions involved in magnetization switching (i.e., current-induced spin torque, heating the island by the tunneling current, and Oersted field effects), thereby providing an improved understanding of the switching mechanism.
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Affiliation(s)
- S Krause
- Institute of Applied Physics and Microstructure Research Center, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany.
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19
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Li Y, Liu BG. Current controlled spin reversal of nanomagnets with giant uniaxial anisotropy. PHYSICAL REVIEW LETTERS 2006; 96:217201. [PMID: 16803269 DOI: 10.1103/physrevlett.96.217201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Indexed: 05/10/2023]
Abstract
Since a giant magnetic anisotropy of 9 meV per atom has been realized on a Pt surface, we use the kinetic Monte Carlo method to study the spin dynamics of a nanomagnet that is made by putting a line of such adatoms on a thin metallic strip so that the fixed spins are coupled very weakly and a spin-polarized current can be injected into the strip. There is a magnetization hysteresis versus the current because of the giant anisotropy. The hysteresis loop is diminished exponentially with the temperature increasing. The magnetization can be controlled by injecting a spin-polarized current.
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Affiliation(s)
- Ying Li
- Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
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20
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Chen TY, Huang SX, Chien CL, Stiles MD. Enhanced magnetoresistance induced by spin transfer torque in granular films with a magnetic field. PHYSICAL REVIEW LETTERS 2006; 96:207203. [PMID: 16803201 DOI: 10.1103/physrevlett.96.207203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Indexed: 05/10/2023]
Abstract
Spin-transfer torques (STT) provide a mechanism to alter the magnetic configurations of magnetic heterostructures, a result previously only achieved by an external magnetic field. In granular solids, we demonstrate a new form of STT effect that can be exploited to induce a large spin disorder when combined with a large magnetic field. We have obtained a very large magnetoresistance effect in excess of 400% at 4.2 K in a large magnetic field, the largest ever reported in any metallic systems. The STT characteristics of granular solids differ significantly from those of multilayers, showing no STT effect at low magnetic fields but prominent STT effects at high fields.
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Affiliation(s)
- T Y Chen
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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21
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Kimura T, Otani Y, Hamrle J. Switching magnetization of a nanoscale ferromagnetic particle using nonlocal spin injection. PHYSICAL REVIEW LETTERS 2006; 96:037201. [PMID: 16486759 DOI: 10.1103/physrevlett.96.037201] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Indexed: 05/06/2023]
Abstract
We have performed nonlocal spin injection into a nanoscale ferromagnetic particle configured in a lateral spin-valve structure to switch its magnetization only by spin current. The nonlocal spin injection aligns the magnetization of the particle parallel to the magnetization of the spin injector. The spin current responsible for switching is estimated from the experiment to be about 200 microA, which is reasonable compared with the values obtained for conventional pillar structures. Interestingly, the switching always occurs from antiparallel to parallel in the particle-injector magnetic configurations, where no opposite switching is observed. Possible reasons for this discrepancy are discussed.
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Affiliation(s)
- T Kimura
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
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22
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Chiba D, Sato Y, Kita T, Matsukura F, Ohno H. Current-driven magnetization reversal in a ferromagnetic semiconductor (Ga,Mn)As/GaAs/(Ga,Mn)As tunnel junction. PHYSICAL REVIEW LETTERS 2004; 93:216602. [PMID: 15601045 DOI: 10.1103/physrevlett.93.216602] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Indexed: 05/24/2023]
Abstract
Current-driven magnetization reversal in a ferromagnetic semiconductor based (Ga,Mn)As/GaAs/(Ga,Mn)As magnetic tunnel junction is demonstrated at 30 K. Magnetoresistance measurements combined with current pulse application on a rectangular 1.5 x 0.3 microm2 device revealed that magnetization switching occurs at low critical current densities of 1.1-2.2 x 10(5) A/cm2 despite the presence of spin-orbit interaction in the p-type semiconductor system. Possible mechanisms responsible for the effect are discussed.
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Affiliation(s)
- D Chiba
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan.
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23
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Krivorotov IN, Emley NC, Garcia AGF, Sankey JC, Kiselev SI, Ralph DC, Buhrman RA. Temperature dependence of spin-transfer-induced switching of nanomagnets. PHYSICAL REVIEW LETTERS 2004; 93:166603. [PMID: 15525019 DOI: 10.1103/physrevlett.93.166603] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Indexed: 05/24/2023]
Abstract
We measure the temperature, magnetic-field, and current dependence for the switching of nanomagnets by a spin-polarized current. Depending on current bias, switching can occur between either two static magnetic states or a static state and a current-driven precessional mode. In both cases, the switching is thermally activated and governed by the sample temperature, not a higher effective magnetic temperature. The activation barriers for switching between static states depend linearly on current, with a weaker dependence for dynamic to static switching.
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24
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Tsoi M, Sun JZ, Parkin SSP. Current-driven excitations in symmetric magnetic nanopillars. PHYSICAL REVIEW LETTERS 2004; 93:036602. [PMID: 15323849 DOI: 10.1103/physrevlett.93.036602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2003] [Indexed: 05/24/2023]
Abstract
We study experimentally the current-driven magnetic excitations in symmetric Co/Cu/Co nanopillars. In contrast with all the previous observations where the current of only one polarity is capable of exciting a multilayer system saturated by an externally applied magnetic field, we observe that both polarities of the applied current trigger excitations in a symmetric multilayer. This may indicate that in symmetric structures the current propels high-frequency magnetic oscillations in all magnetic layers. We argue, however, that only one layer is excited in our multilayers but, interestingly, currents of opposite polarities excite different layers. This hypothesis is supported by modeling the spin accumulation in symmetric magnetic multilayers.
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Affiliation(s)
- M Tsoi
- Physics Department, University of Texas at Austin, Austin, Texas 78712, USA
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25
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Chen TY, Ji Y, Chien CL, Stiles MD. Current-driven switching in a single exchange-biased ferromagnetic layer. PHYSICAL REVIEW LETTERS 2004; 93:026601. [PMID: 15323935 DOI: 10.1103/physrevlett.93.026601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2003] [Indexed: 05/24/2023]
Abstract
We demonstrate spin-transfer torque effects in a single exchange-biased ferromagnetic layer. A current through a point contact to the exchange-biased Co layer reverses the magnetization of a nanodomain in the layer hysteretically for low applied magnetic fields and reversibly for high fields (up to 9 T). These effects are the inverse of the domain wall magnetoresistance, in the same way that similar effects in multilayers are the inverse of giant magnetoresistance.
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Affiliation(s)
- T Y Chen
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
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26
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Jiang Y, Abe S, Ochiai T, Nozaki T, Hirohata A, Tezuka N, Inomata K. Effective reduction of critical current for current-induced magnetization switching by a Ru layer insertion in an exchange-biased spin valve. PHYSICAL REVIEW LETTERS 2004; 92:167204. [PMID: 15169257 DOI: 10.1103/physrevlett.92.167204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Indexed: 05/24/2023]
Abstract
Recently, it has been predicted that a spin-polarized electrical current perpendicular to plane directly flowing through a magnetic element can induce magnetization switching through spin-momentum transfer. In this Letter, the first observation of current-induced magnetization switching (CIMS) in exchange-biased spin valves (ESPVs) at room temperature is reported. The ESPVs show the CIMS behavior under a sweeping dc current with a very high critical current density. It is demonstrated that a thin ruthenium (Ru) layer inserted between a free layer and a top electrode effectively reduces the critical current densities for the CIMS. An "inverse" CIMS behavior is also observed when the thickness of the free layer increases.
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Affiliation(s)
- Y Jiang
- Department of Materials Science, Graduate School of Engineering, Tohoku University, and CREST, Japan Science and Technology Agency, Sendai 980-8579, Japan.
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27
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Koch RH, Katine JA, Sun JZ. Time-resolved reversal of spin-transfer switching in a nanomagnet. PHYSICAL REVIEW LETTERS 2004; 92:088302. [PMID: 14995820 DOI: 10.1103/physrevlett.92.088302] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2003] [Indexed: 05/24/2023]
Abstract
Time-resolved measurements of spin-transfer-induced (STI) magnetization reversal were made in current-perpendicular spin-valve nanomagnetic junctions subject to a pulsed current bias. These results can be understood within the framework of a Landau-Lifshitz-Gilbert equation that includes STI corrections and a Langevin random field for finite temperature. Comparison of these measurements with model calculations demonstrates that spin-transfer induced excitation is responsible for the observed magnetic reversal in these samples.
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Affiliation(s)
- R H Koch
- IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598, USA
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28
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Polianski ML, Brouwer PW. Current-induced transverse spin-wave instability in a thin nanomagnet. PHYSICAL REVIEW LETTERS 2004; 92:026602. [PMID: 14753950 DOI: 10.1103/physrevlett.92.026602] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2003] [Indexed: 05/24/2023]
Abstract
We show that an unpolarized electric current incident perpendicular to the plane of a thin ferromagnet can excite a spin-wave instability transverse to the current direction if source and drain contacts are not symmetric. The instability, which is driven by the current-induced "spin-transfer torque," exists for one current direction only.
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Affiliation(s)
- M L Polianski
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
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29
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Fábián A, Terrier C, Guisan SS, Hoffer X, Dubey M, Gravier L, Ansermet JP, Wegrowe JE. Current-induced two-level fluctuations in pseudo-spin-valve (Co/Cu/Co) nanostructures. PHYSICAL REVIEW LETTERS 2003; 91:257209. [PMID: 14754153 DOI: 10.1103/physrevlett.91.257209] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2003] [Indexed: 05/24/2023]
Abstract
Two-level fluctuations of the magnetization state of pseudo-spin-valve pillars Co(10 nm)/Cu(10 nm)/Co(30 nm) embedded in electrodeposited nanowires ( approximately 40 nm in diameter, 6000 nm in length) are triggered by spin-polarized currents of 10(7) A/cm(2) at room temperature. The statistical properties of the residence times in the parallel and antiparallel magnetization states reveal two effects with qualitatively different dependences on current intensity. The current appears to have the effect of a field determined as the bias field required to equalize these times. The bias field changes sign when the current polarity is reversed. At this field, the effect of a current density of 10(7) A/cm(2) is to lower the mean time for switching down to the microsecond range. This effect is independent of the sign of the current and is interpreted in terms of an effective temperature for the magnetization.
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Affiliation(s)
- A Fábián
- Institut de Physique des Nanostructures, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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30
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Urazhdin S, Birge NO, Pratt WP, Bass J. Current-driven magnetic excitations in permalloy-based multilayer nanopillars. PHYSICAL REVIEW LETTERS 2003; 91:146803. [PMID: 14611545 DOI: 10.1103/physrevlett.91.146803] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2003] [Indexed: 05/24/2023]
Abstract
We study current-driven magnetization switching in nanofabricated Ni(84)Fe(16)/Cu/Ni(84)Fe16 trilayers at 295 and 4.2 K. The shape of the hysteretic switching diagram at low magnetic field changes with temperature. The reversible behavior at higher fields involves two phenomena, a threshold current for magnetic excitations closely correlated with the switching current, and a peak in differential resistance characterized by telegraph noise, with an average period that decreases exponentially with current and shifts with temperature. We interpret both static and dynamic results at 295 and 4.2 K in terms of thermal activation over a potential barrier, with a current-dependent effective magnetic temperature.
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Affiliation(s)
- S Urazhdin
- Department of Physics and Astronomy, Center for Fundamental Materials Research and Center for Sensor Materials, Michigan State University, East Lansing, Michigan 48824, USA
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31
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Ozyilmaz B, Kent AD, Monsma D, Sun JZ, Rooks MJ, Koch RH. Current-induced magnetization reversal in high magnetic fields in Co/Cu/Co nanopillars. PHYSICAL REVIEW LETTERS 2003; 91:067203. [PMID: 12935107 DOI: 10.1103/physrevlett.91.067203] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2002] [Indexed: 05/24/2023]
Abstract
Current-induced magnetization dynamics in Co/Cu/Co trilayer nanopillars (approximately 100 nm in diameter) have been studied experimentally at low temperatures for large applied fields perpendicular to the layers. At 4.2 K an abrupt and hysteretic increase in resistance is observed at high current densities for one polarity of the current, comparable to the giant magnetoresistance effect observed at low fields. A micromagnetic model that includes a spin-transfer torque suggests that the current induces a complete reversal of the thin Co layer to alignment antiparallel to the applied field--that is, to a state of maximum magnetic energy.
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Affiliation(s)
- B Ozyilmaz
- Department of Physics, New York University, New York, New York 10003, USA
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