1
|
Kong C, Song L, Zhao X, Wang H, Zhao J, Yuan G, Zhang X. Enhancing Magnetic Damping under GaAs Band-Edge Photoexcitation in a Co 2FeAl/ n-GaAs Heterojunction. ACS APPLIED MATERIALS & INTERFACES 2024; 16:17041-17050. [PMID: 38517684 DOI: 10.1021/acsami.4c01858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/24/2024]
Abstract
The ultrafast manipulation of spin in ferromagnet-semiconductor (FM/SC) heterojunctions is a key issue for advancing spintronics, where magnetic damping and interfacial spin transport often define device efficiency. Leveraging selective optical excitation in semiconductors offers a unique approach to spin manipulation in FM/SC heterojunctions. Herein, we investigated the magnetic dynamics of a Co2FeAl/n-GaAs heterojunction using the time-resolved magneto-optical Kerr technique and observed the considerably enhanced magnetic damping of Co2FeAl when GaAs is photoexcited near its band edge. This enhancement is attributed to an enhanced spin-pumping effect facilitated by spin-dependent carrier tunneling and capture within the Co2FeAl layer. Moreover, circularly polarized light excites spin-polarized band-edge photocarriers, further impacting the magnetic damping of Co2FeAl through an additional optical spin-transfer torque on the magnetic moment of Co2FeAl. Our results provide a valuable reference for manipulating spin-pumping and interfacial spin transport in FM/SC heterojunctions, showcasing the advantage of optical control of semiconductor photocarriers for the ultrafast manipulation of magnetic dynamics and interfacial spin transfer.
Collapse
Affiliation(s)
- Chongtao Kong
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Lin Song
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xupeng Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Hailong Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guodong Yuan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xinhui Zhang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| |
Collapse
|
2
|
Koinuma Y, Hasegawa S, Sakai M. Long-distance spin communication via ambipolar conductor with electron-hole spin exchange interaction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:135806. [PMID: 38118178 DOI: 10.1088/1361-648x/ad17a5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 12/20/2023] [Indexed: 12/22/2023]
Abstract
Spin accumulation in a nonmagnetic (N) metal embedded between two ferromagnetic metals is still crucial in current spintronics because long-distance spin communication via the N metal can make all-spin logic (ASL) devices feasible. Graphene is almost the only N-region material suitable for ASL devices because its low intrinsic spin-orbit coupling results in a spin diffusion length,ℓN, of over 30µm at room temperature, but long-distance spin communication beyondℓNremains difficult. The present study proposes a way to remove the restriction caused byℓN. In our proposal, an ambipolar conductor, in which electron and hole contribute to electronic conduction and interact with each other, is used for the N-region in a double-heterojunction magnetic structure. When the electron-hole interaction is accompanied by spin exchange, long-distance spin communication characteristic is predicted. Approximately 70 types of ambipolar conductors, including elemental metals and metal alloys, are available. Hence, this material variation may open a new spintronics field, ambipolar spintronics, which may realize operation mechanisms that cannot be achieved using conventional single-band metals. Finally, we present a comprehensive argument on the interface-mediated coupling mechanism between spins and charges, which is the basis of the generation of the spin-coupled interface voltage.
Collapse
Affiliation(s)
- Yukihiro Koinuma
- Division of Material Science, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | | | - Masamichi Sakai
- Division of Material Science, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| |
Collapse
|
3
|
Guarochico-Moreira V, Sambricio JL, Omari K, Anderson CR, Bandurin DA, Toscano-Figueroa JC, Natera-Cordero N, Watanabe K, Taniguchi T, Grigorieva IV, Vera-Marun IJ. Tunable Spin Injection in High-Quality Graphene with One-Dimensional Contacts. NANO LETTERS 2022; 22:935-941. [PMID: 35089714 PMCID: PMC9098166 DOI: 10.1021/acs.nanolett.1c03625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 01/20/2022] [Indexed: 06/09/2023]
Abstract
Spintronics involves the development of low-dimensional electronic systems with potential use in quantum-based computation. In graphene, there has been significant progress in improving spin transport characteristics by encapsulation and reducing impurities, but the influence of standard two-dimensional (2D) tunnel contacts, via pinholes and doping of the graphene channel, remains difficult to eliminate. Here, we report the observation of spin injection and tunable spin signal in fully encapsulated graphene, enabled by van der Waals heterostructures with one-dimensional (1D) contacts. This architecture prevents significant doping from the contacts, enabling high-quality graphene channels, currently with mobilities up to 130 000 cm2 V-1 s-1 and spin diffusion lengths approaching 20 μm. The nanoscale-wide 1D contacts allow spin injection both at room and at low temperature, with the latter exhibiting efficiency comparable with 2D tunnel contacts. At low temperature, the spin signals can be enhanced by as much as an order of magnitude by electrostatic gating, adding new functionality.
Collapse
Affiliation(s)
- Victor
H. Guarochico-Moreira
- Department
of Physics and Astronomy, University of
Manchester, Manchester M13 9PL, U.K.
- Facultad
de Ciencias Naturales y Matemáticas, Escuela Superior Politécnica del Litoral, ESPOL, Campus Gustavo Galindo, Km. 30.5
Vía Perimetral, P.O. Box 09-01-5863, 090902 Guayaquil, Ecuador
| | - Jose L. Sambricio
- Department
of Physics and Astronomy, University of
Manchester, Manchester M13 9PL, U.K.
| | - Khalid Omari
- Department
of Physics and Astronomy, University of
Manchester, Manchester M13 9PL, U.K.
| | | | - Denis A. Bandurin
- Department
of Physics and Astronomy, University of
Manchester, Manchester M13 9PL, U.K.
| | - Jesus C. Toscano-Figueroa
- Department
of Physics and Astronomy, University of
Manchester, Manchester M13 9PL, U.K.
- Consejo
Nacional de Ciencia y Tecnología (CONACyT), Av. Insurgentes Sur 1582, Col. Crédito Constructor, Alcaldía Benito Juarez, C.P. 03940, Ciudad de México, México
| | - Noel Natera-Cordero
- Department
of Physics and Astronomy, University of
Manchester, Manchester M13 9PL, U.K.
- Consejo
Nacional de Ciencia y Tecnología (CONACyT), Av. Insurgentes Sur 1582, Col. Crédito Constructor, Alcaldía Benito Juarez, C.P. 03940, Ciudad de México, México
| | - Kenji Watanabe
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Irina V. Grigorieva
- Department
of Physics and Astronomy, University of
Manchester, Manchester M13 9PL, U.K.
| | - Ivan J. Vera-Marun
- Department
of Physics and Astronomy, University of
Manchester, Manchester M13 9PL, U.K.
| |
Collapse
|
4
|
Ukpong AM. Emergence of Nontrivial Spin Textures in Frustrated Van Der Waals Ferromagnets. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:1770. [PMID: 34361155 PMCID: PMC8308132 DOI: 10.3390/nano11071770] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 11/16/2022]
Abstract
In this work, first principles ground state calculations are combined with the dynamic evolution of a classical spin Hamiltonian to study the metamagnetic transitions associated with the field dependence of magnetic properties in frustrated van der Waals ferromagnets. Dynamically stabilized spin textures are obtained relative to the direction of spin quantization as stochastic solutions of the Landau-Lifshitz-Gilbert-Slonczewski equation under the flow of the spin current. By explicitly considering the spin signatures that arise from geometrical frustrations at interfaces, we may observe the emergence of a magnetic skyrmion spin texture and characterize the formation under competing internal fields. The analysis of coercivity and magnetic hysteresis reveals a dynamic switch from a soft to hard magnetic configuration when considering the spin Hall effect on the skyrmion. It is found that heavy metals in capped multilayer heterostructure stacks host field-tunable spiral skyrmions that could serve as unique channels for carrier transport. The results are discussed to show the possibility of using dynamically switchable magnetic bits to read and write data without the need for a spin transfer torque. These results offer insight to the spin transport signatures that dynamically arise from metamagnetic transitions in spintronic devices.
Collapse
Affiliation(s)
- Aniekan Magnus Ukpong
- Theoretical and Computational Condensed Matter and Materials Physics Group, School of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg 3201, South Africa
| |
Collapse
|
5
|
Panda SN, Majumder S, Bhattacharyya A, Dutta S, Choudhury S, Barman A. Structural Phase-Dependent Giant Interfacial Spin Transparency in W/CoFeB Thin-Film Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2021; 13:20875-20884. [PMID: 33886256 DOI: 10.1021/acsami.1c03776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pure spin current has transformed the research field of conventional spintronics due to its various advantages, including energy efficiency. An efficient mechanism for generation of pure spin current is spin pumping, and high effective spin-mixing conductance (Geff) and interfacial spin transparency (T) are essential for its higher efficiency. By employing the time-resolved magneto-optical Kerr effect technique, we report here a giant value of T in substrate/W (t)/Co20Fe60B20 (d)/SiO2 (2 nm) thin-film heterostructures in the beta-tungsten (β-W) phase. We extract the spin diffusion length of W and spin-mixing conductance of the W/CoFeB interface from the variation of damping as a function of W and CoFeB thickness. This leads to a value of T = 0.81 ± 0.03 for the β-W/CoFeB interface. A stark variation of Geff and T with the thickness of the W layer is obtained in accordance with the structural phase transition and resistivity variation of W with its thickness. Effects such as spin memory loss and two-magnon scattering are found to have minor contributions to damping modulation in comparison to the spin pumping effect which is reconfirmed from the unchanged damping constant with the variation of Cu spacer layer thickness inserted between W and CoFeB. The giant interfacial spin transparency and its strong dependence on crystal structures of W will be important for future spin-orbitronic devices based on pure spin current.
Collapse
Affiliation(s)
- Surya Narayan Panda
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector-III, Salt Lake, Kolkata 700 106, India
| | - Sudip Majumder
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector-III, Salt Lake, Kolkata 700 106, India
| | - Arpan Bhattacharyya
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector-III, Salt Lake, Kolkata 700 106, India
| | - Soma Dutta
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector-III, Salt Lake, Kolkata 700 106, India
| | - Samiran Choudhury
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector-III, Salt Lake, Kolkata 700 106, India
| | - Anjan Barman
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector-III, Salt Lake, Kolkata 700 106, India
| |
Collapse
|
6
|
Khokhriakov D, Karpiak B, Hoque AM, Zhao B, Parui S, Dash SP. Robust Spin Interconnect with Isotropic Spin Dynamics in Chemical Vapor Deposited Graphene Layers and Boundaries. ACS NANO 2020; 14:15864-15873. [PMID: 33136363 PMCID: PMC7690053 DOI: 10.1021/acsnano.0c07163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 10/20/2020] [Indexed: 06/11/2023]
Abstract
The utilization of large-area graphene grown by chemical vapor deposition (CVD) is crucial for the development of scalable spin interconnects in all-spin-based memory and logic circuits. However, the fundamental influence of the presence of multilayer graphene patches and their boundaries on spin dynamics has not been addressed yet, which is necessary for basic understanding and application of robust spin interconnects. Here, we report universal spin transport and dynamic properties in specially devised single layer, bilayer, and trilayer graphene channels and their layer boundaries and folds that are usually present in CVD graphene samples. We observe uniform spin lifetime with isotropic spin relaxation for spins with different orientations in graphene layers and their boundaries at room temperature. In all of the inhomogeneous graphene channels, the spin lifetime anisotropy ratios for spins polarized out-of-plane and in-plane are measured to be close to unity. Our analysis shows the importance of both Elliott-Yafet and D'yakonov-Perel' mechanisms with an increasing role of the latter mechanism in multilayer channels. These results of universal and isotropic spin transport on large-area inhomogeneous CVD graphene with multilayer patches and their boundaries and folds at room temperature prove its outstanding spin interconnect functionality, which is beneficial for the development of scalable spintronic circuits.
Collapse
Affiliation(s)
- Dmitrii Khokhriakov
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-41296, Göteborg, Sweden
| | - Bogdan Karpiak
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-41296, Göteborg, Sweden
| | - Anamul Md. Hoque
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-41296, Göteborg, Sweden
| | - Bing Zhao
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-41296, Göteborg, Sweden
| | | | - Saroj P. Dash
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-41296, Göteborg, Sweden
- Graphene
center, Chalmers University of Technology, SE-41296, Göteborg, Sweden
| |
Collapse
|
7
|
Groesbeck M, Liu H, Kavand M, Lafalce E, Wang J, Pan X, Tennahewa TH, Popli H, Malissa H, Boehme C, Vardeny ZV. Separation of Spin and Charge Transport in Pristine π-Conjugated Polymers. PHYSICAL REVIEW LETTERS 2020; 124:067702. [PMID: 32109121 DOI: 10.1103/physrevlett.124.067702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 10/04/2019] [Accepted: 01/06/2020] [Indexed: 06/10/2023]
Abstract
We have experimentally tested whether spin-transport and charge-transport in pristine π-conjugated polymer films at room temperature occur via the same electronic processes. We have obtained the spin diffusion coefficient of several π-conjugated polymer films from the spin diffusion length measured by the technique of inverse spin Hall effect and the spin relaxation time measured by pulsed electrically detected magnetic resonance spectroscopy. The charge diffusion coefficient was obtained from the time-of-flight mobility measurements on the same films. We found that the spin diffusion coefficient is larger than the charge diffusion coefficient by about 1-2 orders of magnitude and conclude that spin and charge transports in disordered polymer films occur through different electronic processes.
Collapse
Affiliation(s)
- Matthew Groesbeck
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Haoliang Liu
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Marzieh Kavand
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Evan Lafalce
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Jingying Wang
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Xin Pan
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | | | - Henna Popli
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Hans Malissa
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Christoph Boehme
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Z Valy Vardeny
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| |
Collapse
|
8
|
Zhang W, Zhang L, Wong PKJ, Yuan J, Vinai G, Torelli P, van der Laan G, Feng YP, Wee ATS. Magnetic Transition in Monolayer VSe 2 via Interface Hybridization. ACS NANO 2019; 13:8997-9004. [PMID: 31306576 DOI: 10.1021/acsnano.9b02996] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Magnetism in monolayer (ML) VSe2 has attracted broad interest in spintronics, while existing reports have not reached consensus. Using element-specific X-ray magnetic circular dichroism, a magnetic transition in ML VSe2 has been demonstrated at the contamination-free interface between Co and VSe2. Through interfacial hybridization with a Co atomic overlayer, a magnetic moment of about 0.4 μB per V atom in ML VSe2 is revealed, approaching values predicted by previous theoretical calculations. Promotion of the ferromagnetism in ML VSe2 is accompanied by its antiferromagnetic coupling to Co and a reduction in the spin moment of Co. In comparison to the absence of this interface-induced ferromagnetism at the Fe/ML MoSe2 interface, these findings at the Co/ML VSe2 interface provide clear proof that the ML VSe2, initially with magnetic disorder, is on the verge of magnetic transition.
Collapse
Affiliation(s)
- Wen Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
| | - Lei Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
| | - Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546
| | - Jiaren Yuan
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
| | - Giovanni Vinai
- Laboratorio TASC , IOM-CNR , S.S. 14 km 163.5, Basovizza , 34149 Trieste , Italy
| | - Piero Torelli
- Laboratorio TASC , IOM-CNR , S.S. 14 km 163.5, Basovizza , 34149 Trieste , Italy
| | - Gerrit van der Laan
- Magnetic Spectroscopy Group , Diamond Light Source , Didcot OX11 0DE , United Kingdom
| | - Yuan Ping Feng
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
| | - Andrew T S Wee
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
| |
Collapse
|
9
|
Chen S, Yu J, Xie Q, Zhang X, Lin W, Liu L, Zhou J, Shu X, Guo R, Zhang Z, Chen J. Free Field Electric Switching of Perpendicularly Magnetized Thin Film by Spin Current Gradient. ACS APPLIED MATERIALS & INTERFACES 2019; 11:30446-30452. [PMID: 31347362 DOI: 10.1021/acsami.9b09146] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
To realize high-speed nonvolatile magnetic memory with low energy consumption, electric switching of perpendicular magnetization by spin-orbit torque in the heavy metal/ferromagnetic (HM/FM) structure has recently attracted intensive attention. Conventionally, an external in-plane magnetic field for breaking the symmetry is required for achieving electric switching of perpendicular magnetization. However, electric switching without external field is the prerequisite for the integration of magnetic functionality into the integrated circuit devices. Here, we propose a new method of utilizing a W wedge in the Pt/W/FM structure to induce a spin current gradient, which can result in an in-plane equivalent field along the wedge thickness gradient direction. We experimentally demonstrate the deterministic magnetization switching of perpendicular Co/Ni multilayers without external magnetic field when the electric current is along the wedge thickness gradient direction. Our findings shed light on free field electric switching of magnetization by a new physical parameter-an asymmetric spin current induced by a bilayer wedge structure.
Collapse
Affiliation(s)
- Shaohai Chen
- Department of Materials Science and Engineering , National University of Singapore , 117576 , Singapore
| | - Jihang Yu
- Department of Materials Science and Engineering , National University of Singapore , 117576 , Singapore
| | - Qidong Xie
- Department of Materials Science and Engineering , National University of Singapore , 117576 , Singapore
| | - Xiangli Zhang
- Key Lab of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering , Fudan University , Shanghai 200433 , China
| | - Weinan Lin
- Department of Materials Science and Engineering , National University of Singapore , 117576 , Singapore
| | - Liang Liu
- Department of Materials Science and Engineering , National University of Singapore , 117576 , Singapore
| | - Jing Zhou
- Department of Materials Science and Engineering , National University of Singapore , 117576 , Singapore
| | - Xinyu Shu
- Department of Materials Science and Engineering , National University of Singapore , 117576 , Singapore
| | - Rui Guo
- Department of Materials Science and Engineering , National University of Singapore , 117576 , Singapore
| | - Zongzhi Zhang
- Key Lab of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering , Fudan University , Shanghai 200433 , China
| | - Jingsheng Chen
- Department of Materials Science and Engineering , National University of Singapore , 117576 , Singapore
| |
Collapse
|
10
|
Panda SN, Mondal S, Sinha J, Choudhury S, Barman A. All-optical detection of interfacial spin transparency from spin pumping in β-Ta/CoFeB thin films. SCIENCE ADVANCES 2019; 5:eaav7200. [PMID: 31032416 PMCID: PMC6486232 DOI: 10.1126/sciadv.aav7200] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 03/20/2019] [Indexed: 05/31/2023]
Abstract
Generation and utilization of pure spin current have revolutionized energy-efficient spintronic devices. Spin pumping effect generates pure spin current, and for its increased efficiency, spin-mixing conductance and interfacial spin transparency are imperative. The plethora of reports available on generation of spin current with giant magnitude overlook the interfacial spin transparency. Here, we investigate spin pumping in β-Ta/CoFeB thin films by an all-optical time-resolved magneto-optical Kerr effect technique. From variation of Gilbert damping with Ta and CoFeB thicknesses, we extract the spin diffusion length of β-Ta and spin-mixing conductances. Consequently, interfacial spin transparency is derived as 0.50 ± 0.03 from the spin Hall magnetoresistance model for the β-Ta/CoFeB interface. Furthermore, invariance of Gilbert damping with Cu spacer layer thickness inserted between β-Ta and CoFeB layers confirms the absence of other interface effects including spin memory loss. This demonstrates a reliable and noninvasive way to determine interfacial spin transparency and signifies its role in generation of pure spin current by spin pumping effect.
Collapse
Affiliation(s)
- S. N. Panda
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - S. Mondal
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - J. Sinha
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
- Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India
| | - S. Choudhury
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - A. Barman
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| |
Collapse
|
11
|
Zhang W, Wong PKJ, Zhou X, Rath A, Huang Z, Wang H, Morton SA, Yuan J, Zhang L, Chua R, Zeng S, Liu E, Xu F, Chua DHC, Feng YP, van der Laan G, Pennycook SJ, Zhai Y, Wee ATS. Ferromagnet/Two-Dimensional Semiconducting Transition-Metal Dichalcogenide Interface with Perpendicular Magnetic Anisotropy. ACS NANO 2019; 13:2253-2261. [PMID: 30775909 DOI: 10.1021/acsnano.8b08926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Ferromagnet/two-dimensional transition-metal dichalcogenide (FM/2D TMD) interfaces provide attractive opportunities to push magnetic information storage to the atomically thin limit. Existing work has focused on FMs contacted with mechanically exfoliated or chemically vapor-deposition-grown TMDs, where clean interfaces cannot be guaranteed. Here, we report a reliable way to achieve contamination-free interfaces between ferromagnetic CoFeB and molecular-beam epitaxial MoSe2. We show a spin reorientation arising from the interface, leading to a perpendicular magnetic anisotropy (PMA), and reveal the CoFeB/2D MoSe2 interface allowing for the PMA development in a broader CoFeB thickness-range than common systems such as CoFeB/MgO. Using X-ray magnetic circular dichroism analysis, we attribute generation of this PMA to interfacial d-d hybridization and deduce a general rule to enhance its magnitude. We also demonstrate favorable magnetic softness and considerable magnetic moment preserved at the interface and theoretically predict the interfacial band matching for spin filtering. Our work highlights the CoFeB/2D MoSe2 interface as a promising platform for examination of TMD-based spintronic applications and might stimulate further development with other combinations of FM/2D TMD interfaces.
Collapse
Affiliation(s)
- Wen Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
| | - Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
| | - Xiaochao Zhou
- School of Physics , Southeast University , Nanjing 211189 , China
| | - Ashutosh Rath
- Department of Materials Science and Engineering , National University of Singapore , Singapore 117575 , Singapore
| | - Zhaocong Huang
- School of Physics , Southeast University , Nanjing 211189 , China
| | - Hongyu Wang
- Department of Materials Science and Engineering , National University of Singapore , Singapore 117575 , Singapore
| | - Simon A Morton
- Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Jiaren Yuan
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
| | - Lei Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
| | - Rebekah Chua
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- NUS Graduate School for Integrative Sciences and Engineering , National University of Singapore , Centre for Life Sciences, #05-01, 28 Medical Drive , Singapore 117456 Singapore
| | - Shengwei Zeng
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- NUSSNI-NanoCore , National University of Singapore , 5A Engineering Drive 1 , Singapore 117411 , Singapore
| | - Er Liu
- School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Feng Xu
- School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Daniel H C Chua
- Department of Materials Science and Engineering , National University of Singapore , Singapore 117575 , Singapore
| | - Yuan Ping Feng
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
| | | | - Stephen J Pennycook
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
- Department of Materials Science and Engineering , National University of Singapore , Singapore 117575 , Singapore
| | - Ya Zhai
- School of Physics , Southeast University , Nanjing 211189 , China
| | - Andrew T S Wee
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
| |
Collapse
|
12
|
Kimata M, Chen H, Kondou K, Sugimoto S, Muduli PK, Ikhlas M, Omori Y, Tomita T, MacDonald AH, Nakatsuji S, Otani Y. Magnetic and magnetic inverse spin Hall effects in a non-collinear antiferromagnet. Nature 2019; 565:627-630. [DOI: 10.1038/s41586-018-0853-0] [Citation(s) in RCA: 168] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 10/25/2018] [Indexed: 11/09/2022]
|
13
|
Tsai H, Karube S, Kondou K, Yamaguchi N, Ishii F, Otani Y. Clear variation of spin splitting by changing electron distribution at non-magnetic metal/Bi 2O 3 interfaces. Sci Rep 2018; 8:5564. [PMID: 29615800 PMCID: PMC5883063 DOI: 10.1038/s41598-018-23787-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/16/2018] [Indexed: 11/09/2022] Open
Abstract
Large spin splitting at Rashba interface, giving rise to strong spin-momentum locking, is essential for efficient spin-to-charge conversion. Recently, a Cu/Bismuth oxide (Bi2O3) interface has been found to exhibit an efficient spin-to-charge conversion similar to a Ag/Bi interface with large Rashba spin splitting. However, the guiding principle of designing the metal/oxide interface for the efficient conversion has not been clarified yet. Here we report strong non-magnetic (NM) material dependence of spin splitting at NM/Bi2O3 interfaces. We employed spin pumping technique to inject spin current into the interface and evaluated the magnitude of interfacial spin-to-charge conversion. We observed large modulation and sign change in conversion coefficient which corresponds to the variation of spin splitting. Our experimental results together with first-principles calculations indicate that such large variation is caused by material dependent electron distribution near the interface. The results suggest that control of interfacial electron distribution by tuning the difference in work function across the interface may be an effective way to tune the magnitude and sign of spin-to-charge conversion and Rashba parameter at interface.
Collapse
Affiliation(s)
- Hanshen Tsai
- Institute for Solid State Physics, University of Tokyo, Kashiwa, 277-8581, Japan
| | - Shutaro Karube
- Institute for Solid State Physics, University of Tokyo, Kashiwa, 277-8581, Japan
| | - Kouta Kondou
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, 351-0198, Japan.
| | - Naoya Yamaguchi
- Division of Mathematical and Physical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, 920-1192, Japan
| | - Fumiyuki Ishii
- Faculty of Mathematics and Physics, Institute of Science and Engineering, Kanazawa University, Kanazawa, 920-1192, Japan
| | - Yoshichika Otani
- Institute for Solid State Physics, University of Tokyo, Kashiwa, 277-8581, Japan. .,Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, 351-0198, Japan.
| |
Collapse
|
14
|
Du C, van der Sar T, Zhou TX, Upadhyaya P, Casola F, Zhang H, Onbasli MC, Ross CA, Walsworth RL, Tserkovnyak Y, Yacoby A. Control and local measurement of the spin chemical potential in a magnetic insulator. Science 2018; 357:195-198. [PMID: 28706070 DOI: 10.1126/science.aak9611] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 06/09/2017] [Indexed: 12/20/2022]
Abstract
The spin chemical potential characterizes the tendency of spins to diffuse. Probing this quantity could provide insight into materials such as magnetic insulators and spin liquids and aid optimization of spintronic devices. Here we introduce single-spin magnetometry as a generic platform for nonperturbative, nanoscale characterization of spin chemical potentials. We experimentally realize this platform using diamond nitrogen-vacancy centers and use it to investigate magnons in a magnetic insulator, finding that the magnon chemical potential can be controlled by driving the system's ferromagnetic resonance. We introduce a symmetry-based two-fluid theory describing the underlying magnon processes, measure the local thermomagnonic torque, and illustrate the detection sensitivity using electrically controlled spin injection. Our results pave the way for nanoscale control and imaging of spin transport in mesoscopic systems.
Collapse
Affiliation(s)
- Chunhui Du
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA
| | - Toeno van der Sar
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA
| | - Tony X Zhou
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA.,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Pramey Upadhyaya
- Department of Physics and Astronomy, University of California, Los Angeles, 475 Portola Plaza, Los Angeles, CA 90095, USA
| | - Francesco Casola
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA.,Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
| | - Huiliang Zhang
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA.,Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
| | - Mehmet C Onbasli
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.,Koç University, Department of Electrical and Electronics Engineering, Sarıyer, 34450 Istanbul, Turkey
| | - Caroline A Ross
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Ronald L Walsworth
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA.,Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, 475 Portola Plaza, Los Angeles, CA 90095, USA
| | - Amir Yacoby
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA. .,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| |
Collapse
|
15
|
Singh S, Katoch J, Zhu T, Wu RJ, Ahmed AS, Amamou W, Wang D, Mkhoyan KA, Kawakami RK. Strontium Oxide Tunnel Barriers for High Quality Spin Transport and Large Spin Accumulation in Graphene. NANO LETTERS 2017; 17:7578-7585. [PMID: 29129075 DOI: 10.1021/acs.nanolett.7b03543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The quality of the tunnel barrier at the ferromagnet/graphene interface plays a pivotal role in graphene spin valves by circumventing the impedance mismatch problem, decreasing interfacial spin dephasing mechanisms and decreasing spin absorption back into the ferromagnet. It is thus crucial to integrate superior tunnel barriers to enhance spin transport and spin accumulation in graphene. Here, we employ a novel tunnel barrier, strontium oxide (SrO), onto graphene to realize high quality spin transport as evidenced by room-temperature spin relaxation times exceeding a nanosecond in graphene on silicon dioxide substrates. Furthermore, the smooth and pinhole-free SrO tunnel barrier grown by molecular beam epitaxy (MBE), which can withstand large charge injection current densities, allows us to experimentally realize large spin accumulation in graphene at room temperature. This work puts graphene on the path to achieve efficient manipulation of nanomagnet magnetization using spin currents in graphene for logic and memory applications.
Collapse
Affiliation(s)
- Simranjeet Singh
- Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States
| | - Jyoti Katoch
- Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States
| | - Tiancong Zhu
- Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States
| | - Ryan J Wu
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Adam S Ahmed
- Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States
| | - Walid Amamou
- Program of Materials Science and Engineering, University of California , Riverside, California 92521, United States
| | - Dongying Wang
- Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States
| | - K Andre Mkhoyan
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Roland K Kawakami
- Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States
- Program of Materials Science and Engineering, University of California , Riverside, California 92521, United States
| |
Collapse
|
16
|
Large room temperature spin-to-charge conversion signals in a few-layer graphene/Pt lateral heterostructure. Nat Commun 2017; 8:661. [PMID: 28939841 PMCID: PMC5610249 DOI: 10.1038/s41467-017-00563-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 07/10/2017] [Indexed: 11/15/2022] Open
Abstract
Electrical generation and detection of pure spin currents without the need of magnetic materials are key elements for the realization of full electrically controlled spintronic devices. In this framework, achieving a large spin-to-charge conversion signal is crucial, as considerable outputs are needed for plausible applications. Unfortunately, the values obtained so far have been rather low. Here we exploit the spin Hall effect by using Pt, a non-magnetic metal with strong spin-orbit coupling, to generate and detect pure spin currents in a few-layer graphene channel. Furthermore, the outstanding properties of graphene, with long-distance spin transport and higher electrical resistivity than metals, allow us to achieve in our graphene/Pt lateral heterostructures the largest spin-to-charge output voltage at room temperature reported so far in the literature. Our approach opens up exciting opportunities towards the implementation of spin-orbit-based logic circuits and all electrical control of spin information without magnetic field. Spintronic devices with full electrical control rely on electrical generation and detection of spin currents in the absence of magnetic materials. Here, the authors use Pt, a non-magnetic metal, to generate and detect pure spin currents in a few-layer graphene channel, achieving a remarkable spin-to-charge voltage signal at room temperature.
Collapse
|
17
|
Giant magnetoresistance in lateral metallic nanostructures for spintronic applications. Sci Rep 2017; 7:9553. [PMID: 28842573 PMCID: PMC5573406 DOI: 10.1038/s41598-017-09086-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 07/21/2017] [Indexed: 11/09/2022] Open
Abstract
In this letter, we discuss the shift observed in spintronics from the current-perpendicular-to-plane geometry towards lateral geometries, illustrating the new opportunities offered by this configuration. Using CoFe-based all-metallic LSVs, we show that giant magnetoresistance variations of more than 10% can be obtained, competitive with the current-perpendicular-to-plane giant magnetoresistance. We then focus on the interest of being able to tailor freely the geometries. On the one hand, by tailoring the non-magnetic parts, we show that it is possible to enhance the spin signal of giant magnetoresistance structures. On the other hand, we show that tailoring the geometry of lateral structures allows creating a multilevel memory with high spin signals, by controlling the coercivity and shape anisotropy of the magnetic parts. Furthermore, we study a new device in which the magnetization direction of a nanodisk can be detected. We thus show that the ability to control the magnetic properties can be used to take advantage of all the spin degrees of freedom, which are usually occulted in current-perpendicular-to-plane devices. This flexibility of lateral structures relatively to current-perpendicular-to-plane structures is thus found to offer a new playground for the development of spintronic applications.
Collapse
|
18
|
Hellman F, Hoffmann A, Tserkovnyak Y, Beach GSD, Fullerton EE, Leighton C, MacDonald AH, Ralph DC, Arena DA, Dürr HA, Fischer P, Grollier J, Heremans JP, Jungwirth T, Kimel AV, Koopmans B, Krivorotov IN, May SJ, Petford-Long AK, Rondinelli JM, Samarth N, Schuller IK, Slavin AN, Stiles MD, Tchernyshyov O, Thiaville A, Zink BL. Interface-Induced Phenomena in Magnetism. REVIEWS OF MODERN PHYSICS 2017; 89:025006. [PMID: 28890576 PMCID: PMC5587142 DOI: 10.1103/revmodphys.89.025006] [Citation(s) in RCA: 192] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions. It starts with an introduction and overview of how basic magnetic properties are affected by interfaces, then turns to a discussion of charge and spin transport through and near interfaces and how these can be used to control the properties of the magnetic layer. Important concepts include spin accumulation, spin currents, spin transfer torque, and spin pumping. An overview is provided to the current state of knowledge and existing review literature on interfacial effects such as exchange bias, exchange spring magnets, spin Hall effect, oxide heterostructures, and topological insulators. The article highlights recent discoveries of interface-induced magnetism and non-collinear spin textures, non-linear dynamics including spin torque transfer and magnetization reversal induced by interfaces, and interfacial effects in ultrafast magnetization processes.
Collapse
Affiliation(s)
- Frances Hellman
- Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Geoffrey S D Beach
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Eric E Fullerton
- Center for Memory and Recording Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0401, USA
| | - Chris Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Allan H MacDonald
- Department of Physics, University of Texas at Austin, Austin, Texas 78712-0264, USA
| | - Daniel C Ralph
- Physics Department, Cornell University, Ithaca, New York 14853, USA; Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, USA
| | - Dario A Arena
- Department of Physics, University of South Florida, Tampa, Florida 33620-7100, USA
| | - Hermann A Dürr
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Physics Department, University of California, 1156 High Street, Santa Cruz, California 94056, USA
| | - Julie Grollier
- Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Avenue Fresnel, 91767 Palaiseau, France
| | - Joseph P Heremans
- Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Tomas Jungwirth
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53 Praha 6, Czech Republic; School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Alexey V Kimel
- Radboud University, Institute for Molecules and Materials, Nijmegen 6525 AJ, The Netherlands
| | - Bert Koopmans
- Department of Applied Physics, Center for NanoMaterials, COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Ilya N Krivorotov
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Steven J May
- Department of Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - Amanda K Petford-Long
- Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, USA
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ivan K Schuller
- Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, California 92093, USA; Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Andrei N Slavin
- Department of Physics, Oakland University, Rochester, Michigan 48309, USA
| | - Mark D Stiles
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6202, USA
| | - Oleg Tchernyshyov
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - André Thiaville
- Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris-Sud, 91405 Orsay, France
| | - Barry L Zink
- Department of Physics and Astronomy, University of Denver, Denver, CO 80208, USA
| |
Collapse
|
19
|
Kim KW, O'Brien L, Crowell PA, Leighton C, Stiles MD. Theory of Kondo suppression of spin polarization in nonlocal spin valves. PHYSICAL REVIEW. B 2017; 95:104404. [PMID: 28758157 PMCID: PMC5531311 DOI: 10.1103/physrevb.95.104404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We theoretically analyze contributions from the Kondo effect to the spin polarization and spin diffusion length in all-metal nonlocal spin valves. Interdiffusion of ferromagnetic atoms into the normal metal layer creates a region in which Kondo physics plays a significant role, giving discrepancies between experiment and existing theory. We start from a simple model and construct a modified spin drift-diffusion equation which clearly demonstrates how the Kondo physics not only suppresses the electrical conductivity but even more strongly reduces the spin diffusion length. We also present an explicit expression for the suppression of spin polarization due to Kondo physics in an illustrative regime. We compare this theory to previous experimental data to extract an estimate of the Elliot-Yafet probability for Kondo spin flip scattering of 0.7 ± 0.4, in good agreement with the value of 2/3 derived in the original theory of Kondo.
Collapse
Affiliation(s)
- K-W Kim
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Maryland NanoCenter, University of Maryland, College Park, Maryland 20742, USA
- Institut für Physik, Johannes Gutenberg Universitat Mainz, Mainz 55128, Germany
| | - L O'Brien
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minnesota 55455, USA
- Thin Film Magnetism, Cavendish Laboratory, University of Cambridge, CB3 0HE, UK
- Department of Physics, University of Liverpool, Liverpool L69 7ZE, UK
| | - P A Crowell
- School of Physics and Astronomy, University of Minnesota, Minnesota 55455, USA
| | - C Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minnesota 55455, USA
| | - M D Stiles
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| |
Collapse
|
20
|
Oyarzún S, Nandy AK, Rortais F, Rojas-Sánchez JC, Dau MT, Noël P, Laczkowski P, Pouget S, Okuno H, Vila L, Vergnaud C, Beigné C, Marty A, Attané JP, Gambarelli S, George JM, Jaffrès H, Blügel S, Jamet M. Evidence for spin-to-charge conversion by Rashba coupling in metallic states at the Fe/Ge(111) interface. Nat Commun 2016; 7:13857. [PMID: 27976747 PMCID: PMC5171917 DOI: 10.1038/ncomms13857] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 11/04/2016] [Indexed: 12/13/2022] Open
Abstract
The spin-orbit coupling relating the electron spin and momentum allows for spin generation, detection and manipulation. It thus fulfils the three basic functions of the spin field-effect transistor. However, the spin Hall effect in bulk germanium is too weak to produce spin currents, whereas large Rashba effect at Ge(111) surfaces covered with heavy metals could generate spin-polarized currents. The Rashba spin splitting can actually be as large as hundreds of meV. Here we show a giant spin-to-charge conversion in metallic states at the Fe/Ge(111) interface due to the Rashba coupling. We generate very large charge currents by direct spin pumping into the interface states from 20 K to room temperature. The presence of these metallic states at the Fe/Ge(111) interface is demonstrated by first-principles electronic structure calculations. By this, we demonstrate how to take advantage of the spin-orbit coupling for the development of the spin field-effect transistor.
Collapse
Affiliation(s)
- S Oyarzún
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
- Departamento de Fisica, CEDENNA, Universidad de Santiago de Chile (USACH), 9170124 Santiago, Chile
| | - A K Nandy
- Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | - F Rortais
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - J-C Rojas-Sánchez
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - M-T Dau
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - P Noël
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - P Laczkowski
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - S Pouget
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - H Okuno
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - L Vila
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - C Vergnaud
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - C Beigné
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - A Marty
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - J-P Attané
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - S Gambarelli
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| | - J-M George
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - H Jaffrès
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - S Blügel
- Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | - M Jamet
- Institut des Nanosciences et l'Energie Atomique et Cryogénie, INAC, Commissariat á aux Energies Alternatives-Univ. Grenoble Alpes, 17 rue des Martyrs, F-38000 Grenoble, France
- CEA, INAC, F-38000 Grenoble, France
| |
Collapse
|
21
|
Murphy BA, Vick AJ, Samiepour M, Hirohata A. Highly Efficient Spin-Current Operation in a Cu Nano-Ring. Sci Rep 2016; 6:37398. [PMID: 27869213 PMCID: PMC5116585 DOI: 10.1038/srep37398] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 10/27/2016] [Indexed: 11/17/2022] Open
Abstract
An all-metal lateral spin-valve structure has been fabricated with a medial Copper nano-ring to split the diffusive spin-current path. We have demonstrated significant modulation of the non-local signal by the application of a magnetic field gradient across the nano-ring, which is up to 30% more efficient than the conventional Hanle configuration at room temperature. This was achieved by passing a dc current through a current-carrying bar to provide a locally induced Ampère field. We have shown that in this manner a lateral spin-valve gains an additional functionality in the form of three-terminal gate operation for future spintronic logic.
Collapse
Affiliation(s)
- Benedict A Murphy
- Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Andrew J Vick
- Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom.,Department of Electronics, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Marjan Samiepour
- Department of Electronics, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Atsufumi Hirohata
- Department of Electronics, University of York, Heslington, York YO10 5DD, United Kingdom
| |
Collapse
|
22
|
Kapilashrami M, Wang YJ, Li X, Glans PA, Fang M, Riazanova AV, Belova LM, Rao KV, Luo Y, Barbiellini B, Lin H, Markiewicz R, Bansil A, Hussain Z, Guo J. Understanding the magnetic interaction between intrinsic defects and impurity ions in room-temperature ferromagnetic Mg1-xFexO thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:156002. [PMID: 26987741 DOI: 10.1088/0953-8984/28/15/156002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Understanding the nature and characteristics of the intrinsic defects and impurities in the dielectric barrier separating the ferromagnetic electrodes in a magnetic tunneling junction is of great importance for understanding the often observed 'barrier-breakdown' therein. In this connection, we present herein systematic experimental (SQUID and synchrotron-radiation-based x-ray absorption spectroscopy) and computational studies on the electronic and magnetic properties of Mg1-xFexO thin films. Our studies reveal: (i) defect aggregates comprised of basic and trimer units (Fe impurity coupled to 1 or 2 Mg vacancies) and (ii) existence of two competing magnetic orders, defect- and dopant-induced, with spin densities aligning anti-parallel if the trimer is present in the oxide matrix. These findings open up new avenues for designing tunneling barriers with high endurance and tunneling effect upon tuning the concentration/distribution of the two magnetic orders.
Collapse
Affiliation(s)
- Mukes Kapilashrami
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Center for Engineering Concepts Development, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Zahnd G, Vila L, Pham TV, Marty A, Laczkowski P, Savero Torres W, Beigné C, Vergnaud C, Jamet M, Attané JP. Comparison of the use of NiFe and CoFe as electrodes for metallic lateral spin valves. NANOTECHNOLOGY 2016; 27:035201. [PMID: 26637104 DOI: 10.1088/0957-4484/27/3/035201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Spin injection and detection in Co60Fe40-based all-metallic lateral spin valves have been studied at both room and low temperatures. The obtained spin signals amplitudes have been compared to those of identical Ni80Fe20-based devices. The replacement of Ni80Fe20 by CoFe allows increasing the spin signal amplitude by up to one order of magnitude, thus reaching 50 mΩ at room temperature. The spin signal dependence with the distance between the ferromagnetic electrodes has been analyzed using both a 1D spin-transport model and finite element method simulations. The enhancement of the spin signal amplitude when using CoFe electrodes can be explained by a higher effective polarization.
Collapse
Affiliation(s)
- G Zahnd
- Université Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France. CEA, Institut Nanosciences et Cryogénie, SP2M, F-38000 Grenoble, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Current-limiting challenges for all-spin logic devices. Sci Rep 2015; 5:14905. [PMID: 26449410 PMCID: PMC4598875 DOI: 10.1038/srep14905] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/11/2015] [Indexed: 11/30/2022] Open
Abstract
All-spin logic device (ASLD) has attracted increasing interests as one of the most promising post-CMOS device candidates, thanks to its low power, non-volatility and logic-in-memory structure. Here we investigate the key current-limiting factors and develop a physics-based model of ASLD through nano-magnet switching, the spin transport properties and the breakdown characteristic of channel. First, ASLD with perpendicular magnetic anisotropy (PMA) nano-magnet is proposed to reduce the critical current (Ic0). Most important, the spin transport efficiency can be enhanced by analyzing the device structure, dimension, contact resistance as well as material parameters. Furthermore, breakdown current density (JBR) of spin channel is studied for the upper current limitation. As a result, we can deduce current-limiting conditions and estimate energy dissipation. Based on the model, we demonstrate ASLD with different structures and channel materials (graphene and copper). Asymmetric structure is found to be the optimal option for current limitations. Copper channel outperforms graphene in term of energy but seriously suffers from breakdown current limit. By exploring the current limit and performance tradeoffs, the optimization of ASLD is also discussed. This benchmarking model of ASLD opens up new prospects for design and implementation of future spintronics applications.
Collapse
|
25
|
Zhang HJ, Yamamoto S, Gu B, Li H, Maekawa M, Fukaya Y, Kawasuso A. Charge-to-Spin Conversion and Spin Diffusion in Bi/Ag Bilayers Observed by Spin-Polarized Positron Beam. PHYSICAL REVIEW LETTERS 2015; 114:166602. [PMID: 25955066 DOI: 10.1103/physrevlett.114.166602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Indexed: 06/04/2023]
Abstract
Charge-to-spin conversion induced by the Rashba-Edelstein effect was directly observed for the first time in samples with no magnetic layer. A spin-polarized positron beam was used to probe the spin polarization of the outermost surface electrons of Bi/Ag/Al2O3 and Ag/Bi/Al2O3 when charge currents were only associated with the Ag layers. An opposite surface spin polarization was found between Bi/Ag/Al2O3 and Ag/Bi/Al2O3 samples with the application of a charge current in the same direction. The surface spin polarizations of both systems decreased exponentially with the outermost layer thickness, suggesting the occurrence of spin diffusion from the Bi/Ag interface to the outermost surfaces. This work provides a new technique to measure spin diffusion length.
Collapse
Affiliation(s)
- H J Zhang
- Advanced Science Research Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
| | - S Yamamoto
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
| | - B Gu
- Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai-mura, Ibaraki 319-1195, Japan
| | - H Li
- Advanced Science Research Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
| | - M Maekawa
- Advanced Science Research Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
| | - Y Fukaya
- Advanced Science Research Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
| | - A Kawasuso
- Advanced Science Research Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
| |
Collapse
|
26
|
Silaev M, Virtanen P, Bergeret FS, Heikkilä TT. Long-range spin accumulation from heat injection in mesoscopic superconductors with Zeeman splitting. PHYSICAL REVIEW LETTERS 2015; 114:167002. [PMID: 25955071 DOI: 10.1103/physrevlett.114.167002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Indexed: 06/04/2023]
Abstract
We describe far-from-equilibrium nonlocal transport in a diffusive superconducting wire with a Zeeman splitting, taking into account different spin relaxation mechanisms. We demonstrate that due to the Zeeman splitting, an injection of current in a superconducting wire creates spin accumulation that can only relax via thermalization. This effect leads to a long-range spin accumulation detectable in the nonlocal signal. Our model gives a qualitative explanation and provides accurate fits of recent experimental results in terms of realistic parameters.
Collapse
Affiliation(s)
- M Silaev
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
- Department of Theoretical Physics, The Royal Institute of Technology, Stockholm SE-10691, Sweden
| | - P Virtanen
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
| | - F S Bergeret
- Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, and Donostia International Physics Center (DIPC), Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
| | - T T Heikkilä
- University of Jyväskylä, Department of Physics and Nanoscience Center, P.O. Box 35 (YFL), FI-40014 Jyväskylä, Finland
| |
Collapse
|
27
|
Bandyopadhyay S, Hossain MI, Ahmad H, Atulasimha J, Bandyopadhyay S. Coherent spin transport and suppression of spin relaxation in InSb nanowires with single subband occupancy at room temperature. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:4379-4385. [PMID: 25048330 DOI: 10.1002/smll.201401022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Revised: 06/15/2014] [Indexed: 06/03/2023]
Abstract
A longstanding goal of spintronics is to inject, then coherently transport, and finally detect electron spins in a semiconductor nanowire in which a single quantized subband is occupied by the electrons at room temperature. Here, the achieving of this goal in electrochemically self-assembled 50-nm diameter InSb nanowires is reported and substantiated by demonstrating both the spin-valve effect and the Hanle effect. Observing both effects in the same sample allows one to estimate the electron mobility and the spin relaxation time in the nanowires. It is found that despite four orders of magnitude degradation in the mobility compared to bulk or quantum wells and a resulting four orders of magnitude increase in the Elliott-Yafet spin relaxation rate, the spin relaxation time in the nanowires is still about an order of magnitude longer than what has been reported in bulk and quantum wells. This is caused by the elimination or suppression of the D'yakonov-Perel' spin relaxation through single subband occupancy. These experiments shed light on the nature of spin transport in a true quantum wire and raise hopes for the realization of a room-temperature Datta-Das spin transistor, where single subband occupancy is critical for optimum performance.
Collapse
Affiliation(s)
- Saumil Bandyopadhyay
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA; Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | | | | | | | | |
Collapse
|
28
|
O'Brien L, Erickson MJ, Spivak D, Ambaye H, Goyette RJ, Lauter V, Crowell PA, Leighton C. Kondo physics in non-local metallic spin transport devices. Nat Commun 2014; 5:3927. [PMID: 24873934 DOI: 10.1038/ncomms4927] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 04/22/2014] [Indexed: 11/09/2022] Open
Abstract
The non-local spin-valve is pivotal in spintronics, enabling separation of charge and spin currents, disruptive potential applications and the study of pressing problems in the physics of spin injection and relaxation. Primary among these problems is the perplexing non-monotonicity in the temperature-dependent spin accumulation in non-local ferromagnetic/non-magnetic metal structures, where the spin signal decreases at low temperatures. Here we show that this effect is strongly correlated with the ability of the ferromagnetic to form dilute local magnetic moments in the NM. This we achieve by studying a significantly expanded range of ferromagnetic/non-magnetic combinations. We argue that local moments, formed by ferromagnetic/non-magnetic interdiffusion, suppress the injected spin polarization and diffusion length via a manifestation of the Kondo effect, thus explaining all observations. We further show that this suppression can be completely quenched, even at interfaces that are highly susceptible to the effect, by insertion of a thin non-moment-supporting interlayer.
Collapse
Affiliation(s)
- L O'Brien
- 1] Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA [2] Thin Film Magnetism, Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
| | - M J Erickson
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - D Spivak
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - H Ambaye
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - R J Goyette
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - V Lauter
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - P A Crowell
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - C Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| |
Collapse
|
29
|
Sun D, Ehrenfreund E, Valy Vardeny Z. The first decade of organic spintronics research. Chem Commun (Camb) 2014; 50:1781-93. [DOI: 10.1039/c3cc47126h] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The significant milestones in organic spintronics achieved during the first decade of research are reviewed.
Collapse
Affiliation(s)
- Dali Sun
- Department of Physics and Astronomy
- University of Utah
- Salt Lake City, USA
| | - Eitan Ehrenfreund
- Physics Department
- Technion-Israel Institute of Technology
- Haifa, Israel
| | - Z. Valy Vardeny
- Department of Physics and Astronomy
- University of Utah
- Salt Lake City, USA
| |
Collapse
|
30
|
Li P, Li J, Qing L, Dery H, Appelbaum I. Anisotropy-driven spin relaxation in germanium. PHYSICAL REVIEW LETTERS 2013; 111:257204. [PMID: 24483755 DOI: 10.1103/physrevlett.111.257204] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Indexed: 06/03/2023]
Abstract
A unique spin depolarization mechanism, induced by the presence of g-factor anisotropy and intervalley scattering, is revealed by spin-transport measurements on long-distance germanium devices in a magnetic field longitudinal to the initial spin orientation. The confluence of electron-phonon scattering (leading to Elliott-Yafet spin flips) and this previously unobserved physics enables the extraction of spin lifetime solely from spin-valve measurements, without spin precession, and in a regime of substantial electric-field-generated carrier heating. We find spin lifetimes in Ge up to several hundreds of nanoseconds at low temperature, far beyond any other available experimental results.
Collapse
Affiliation(s)
- Pengke Li
- Department of Physics and Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, USA and Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA
| | - Jing Li
- Department of Physics and Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, USA
| | - Lan Qing
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
| | - Hanan Dery
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA and Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
| | - Ian Appelbaum
- Department of Physics and Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, USA
| |
Collapse
|
31
|
Spin-to-charge conversion using Rashba coupling at the interface between non-magnetic materials. Nat Commun 2013; 4:2944. [DOI: 10.1038/ncomms3944] [Citation(s) in RCA: 565] [Impact Index Per Article: 51.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 11/14/2013] [Indexed: 11/08/2022] Open
|
32
|
Fujiwara K, Fukuma Y, Matsuno J, Idzuchi H, Niimi Y, Otani Y, Takagi H. 5d iridium oxide as a material for spin-current detection. Nat Commun 2013; 4:2893. [DOI: 10.1038/ncomms3893] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 11/07/2013] [Indexed: 11/09/2022] Open
|
33
|
de Oliveira TVAG, Gobbi M, Porro JM, Hueso LE, Bittner AM. Charge and spin transport in PEDOT:PSS nanoscale lateral devices. NANOTECHNOLOGY 2013; 24:475201. [PMID: 24177495 DOI: 10.1088/0957-4484/24/47/475201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The electrical transport of the highly conductive poly-(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) is investigated with Ohmic and spin-polarized tunnel contacts at nanoscale lateral dimensions. Temperature-dependent charge transport measurements reveal that electrical conductivity scales non-linearly as a function of electrode spacing, which is attributed to the localization of carriers induced by the disorder introduced by the PSS polyelectrolyte. In addition, we demonstrate the integration of this conducting polymer in nanoscale lateral spin-valve devices by increasing the pH of the PEDOT:PSS solution. We present charge and magnetotransport measurement results of NiFe/AlOx/PEDOT:PSS/AlOx/NiFe lateral structures for various thicknesses of the alumina tunnel barriers. We discuss the absence of magnetoresistance of our spin valves within the framework of Valet-Fert theory, and estimate an upper limit for the spin lifetime of carriers in PEDOT:PSS to τsf ≤ 50 ns.
Collapse
|
34
|
Niimi Y, Wei D, Idzuchi H, Wakamura T, Kato T, Otani Y. Experimental verification of comparability between spin-orbit and spin-diffusion lengths. PHYSICAL REVIEW LETTERS 2013; 110:016805. [PMID: 23383824 DOI: 10.1103/physrevlett.110.016805] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Indexed: 06/01/2023]
Abstract
We experimentally confirmed that the spin-orbit lengths of noble metals obtained from weak antilocalization measurements are comparable to the spin diffusion lengths determined from lateral spin valve ones. Even for metals with strong spin-orbit interactions such as Pt, we verified that the two methods gave comparable values which were much larger than those obtained from recent spin torque ferromagnetic resonance measurements. To give a further evidence for the comparability between the two length scales, we measured the disorder dependence of the spin-orbit length of copper by changing the thickness of the wire. The obtained spin-orbit length nicely follows a linear law as a function of the diffusion coefficient, clearly indicating that the Elliott-Yafet mechanism is dominant as in the case of the spin diffusion length.
Collapse
Affiliation(s)
- Yasuhiro Niimi
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
| | | | | | | | | | | |
Collapse
|
35
|
Idzuchi H, Fukuma Y, Otani Y. Towards coherent spin precession in pure-spin current. Sci Rep 2012; 2:628. [PMID: 22953049 PMCID: PMC3432863 DOI: 10.1038/srep00628] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 08/15/2012] [Indexed: 11/17/2022] Open
Abstract
Non-local spin injection in lateral spin valves generates a pure spin current which is a diffusive flow of spins (i.e. spin angular momentums) with no net charge flow. The diffusive spins lose phase coherency in precession while undergoing frequent collisions and these events lead to a broad distribution of the dwell time in a transport channel between the injector and the detector. Here we show the lateral spin-valves with dual injectors enable us to detect a genuine in-plane precession signal from the Hanle effect, demonstrating the phase coherency in the in-plane precession is improved with an increase of the channel length. The coherency in the spin precession shows a universal behavior as a function of the normalized separation between the injector and the detector in material-independent fashion for metals and semiconductors including graphene.
Collapse
Affiliation(s)
- Hiroshi Idzuchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- Advanced Science Institute, RIKEN, 2-1, Wako 351-0198, Japan
| | - Yasuhiro Fukuma
- Advanced Science Institute, RIKEN, 2-1, Wako 351-0198, Japan
- Frontier Research Academy for Young Researchers, Kyushu Institute of Technology, Iizuka 820-8502, Japan
| | - YoshiChika Otani
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- Advanced Science Institute, RIKEN, 2-1, Wako 351-0198, Japan
| |
Collapse
|
36
|
Cascales JP, Herranz D, Aliev FG, Szczepański T, Dugaev VK, Barnaś J, Duluard A, Hehn M, Tiusan C. Controlling shot noise in double-barrier magnetic tunnel junctions. PHYSICAL REVIEW LETTERS 2012; 109:066601. [PMID: 23006290 DOI: 10.1103/physrevlett.109.066601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/30/2012] [Indexed: 06/01/2023]
Abstract
We demonstrate that shot noise in Fe/MgO/Fe/MgO/Fe double-barrier magnetic tunnel junctions is determined by the relative magnetic configuration of the junction and also by the asymmetry of the barriers. The proposed theoretical model, based on sequential tunneling through the system and including spin relaxation, successfully accounts for the experimental observations for bias voltages below 0.5 V, where the influence of quantum well states is negligible. A weak enhancement of conductance and shot noise, observed at some voltages (especially above 0.5 V), indicates the formation of quantum well states in the middle magnetic layer. The observed results open up new perspectives for a reliable magnetic control of the most fundamental noise in spintronic structures.
Collapse
Affiliation(s)
- J P Cascales
- Departmento Fisica Materia Condensada, Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|