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1
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Huang X, Chen X, Li Y, Mangeri J, Zhang H, Ramesh M, Taghinejad H, Meisenheimer P, Caretta L, Susarla S, Jain R, Klewe C, Wang T, Chen R, Hsu CH, Harris I, Husain S, Pan H, Yin J, Shafer P, Qiu Z, Rodrigues DR, Heinonen O, Vasudevan D, Íñiguez J, Schlom DG, Salahuddin S, Martin LW, Analytis JG, Ralph DC, Cheng R, Yao Z, Ramesh R. Manipulating chiral spin transport with ferroelectric polarization. Nat Mater 2024:10.1038/s41563-024-01854-8. [PMID: 38622325 DOI: 10.1038/s41563-024-01854-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 03/07/2024] [Indexed: 04/17/2024]
Abstract
A magnon is a collective excitation of the spin structure in a magnetic insulator and can transmit spin angular momentum with negligible dissipation. This quantum of a spin wave has always been manipulated through magnetic dipoles (that is, by breaking time-reversal symmetry). Here we report the experimental observation of chiral spin transport in multiferroic BiFeO3 and its control by reversing the ferroelectric polarization (that is, by breaking spatial inversion symmetry). The ferroelectrically controlled magnons show up to 18% modulation at room temperature. The spin torque that the magnons in BiFeO3 carry can be used to efficiently switch the magnetization of adjacent magnets, with a spin-torque efficiency comparable to the spin Hall effect in heavy metals. Utilizing such controllable magnon generation and transmission in BiFeO3, an all-oxide, energy-scalable logic is demonstrated composed of spin-orbit injection, detection and magnetoelectric control. Our observations open a new chapter of multiferroic magnons and pave another path towards low-dissipation nanoelectronics.
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Affiliation(s)
- Xiaoxi Huang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Xianzhe Chen
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Yuhang Li
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, USA
| | - John Mangeri
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, Esch/Alzette, Luxembourg
| | - Hongrui Zhang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Maya Ramesh
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA
| | | | - Peter Meisenheimer
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Lucas Caretta
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Sandhya Susarla
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Rakshit Jain
- Department of Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Tianye Wang
- Department of Physics, University of California, Berkeley, CA, USA
| | - Rui Chen
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Cheng-Hsiang Hsu
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA
| | - Isaac Harris
- Department of Physics, University of California, Berkeley, CA, USA
| | - Sajid Husain
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Hao Pan
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Jia Yin
- Applied Mathematics and Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Ziqiang Qiu
- Department of Physics, University of California, Berkeley, CA, USA
| | - Davi R Rodrigues
- Department of Electrical Engineering, Politecnico di Bari, Bari, Italy
| | - Olle Heinonen
- Materials Science Division, Argonne National Laboratory, Lemont, IL, USA
| | - Dilip Vasudevan
- Applied Mathematics and Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jorge Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, Esch/Alzette, Luxembourg
- Department of Physics and Materials Science, University of Luxembourg, Belvaux, Luxembourg
| | - Darrell G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA
| | - Sayeef Salahuddin
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - James G Analytis
- Department of Physics, University of California, Berkeley, CA, USA
- CIFAR Quantum Materials, CIFAR, Toronto, Ontario, Canada
| | - Daniel C Ralph
- Department of Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA
| | - Ran Cheng
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, USA
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Zhi Yao
- Applied Mathematics and Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Physics, University of California, Berkeley, CA, USA.
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2
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Zhang H, Chen X, Wang T, Huang X, Chen X, Shao YT, Meng F, Meisenheimer P, N'Diaye A, Klewe C, Shafer P, Pan H, Jia Y, Crommie MF, Martin LW, Yao J, Qiu Z, Muller DA, Birgeneau RJ, Ramesh R. Room-Temperature, Current-Induced Magnetization Self-Switching in A Van Der Waals Ferromagnet. Adv Mater 2024; 36:e2308555. [PMID: 38016700 DOI: 10.1002/adma.202308555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/30/2023] [Indexed: 11/30/2023]
Abstract
2D layered materials with broken inversion symmetry are being extensively pursued as spin source layers to realize high-efficiency magnetic switching. Such low-symmetry layered systems are, however, scarce. In addition, most layered magnets with perpendicular magnetic anisotropy show a low Curie temperature. Here, the experimental observation of spin-orbit torque magnetization self-switching at room temperature in a layered polar ferromagnetic metal, Fe2.5 Co2.5 GeTe2 is reported. The spin-orbit torque is generated from the broken inversion symmetry along the c-axis of the crystal. These results provide a direct pathway toward applicable 2D spintronic devices.
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Affiliation(s)
- Hongrui Zhang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Xiang Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Tianye Wang
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Xiaoxi Huang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Xianzhe Chen
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yu-Tsun Shao
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089, USA
| | - Fanhao Meng
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Peter Meisenheimer
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Alpha N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Hao Pan
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Yanli Jia
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Michael F Crommie
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Departments of Materials Science and NanoEngineering, Chemistry, and Physics and Astronomy, Rice University, Houston, TX, 77005, USA
- Rice Advanced Materials Institute, Rice University, Houston, TX, 77005, USA
| | - Jie Yao
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ziqiang Qiu
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA
| | - Robert J Birgeneau
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
- Department of Physics and Astronomy, Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
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3
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Feng M, Ahlm N, Sasaki DY, Chiu IT, N’Diaye AT, Shafer P, Klewe C, Mehta A, Takamura Y. Tuning In-Plane Magnetic Anisotropy and Interfacial Exchange Coupling in Epitaxial La 2/3Sr 1/3CoO 3/La 2/3Sr 1/3MnO 3 Heterostructures. ACS Appl Mater Interfaces 2023; 15. [PMID: 37910813 PMCID: PMC10658449 DOI: 10.1021/acsami.3c10376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 09/18/2023] [Accepted: 10/16/2023] [Indexed: 11/03/2023]
Abstract
Controlling the in-plane magnetocrystalline anisotropy and interfacial exchange coupling between ferromagnetic (FM) layers plays a key role in next-generation spintronic and magnetic memory devices. In this work, we explored the effect of tuning the magnetocrystalline anisotropy of La2/3Sr1/3CoO3 (LSCO) and La2/3Sr1/3MnO3 (LSMO) layers and the corresponding effect on interfacial exchange coupling by adjusting the thickness of the LSCO layer (tLSCO). The epitaxial LSCO/LSMO bilayers were grown on (110)o-oriented NdGaO3 (NGO) substrates with a fixed LSMO (top layer) thickness of 6 nm and LSCO (bottom layer) thicknesses varying from 1 to 10 nm. Despite the small difference (∼0.2%) in lattice mismatch between the two in-plane directions, [001]o and [11̅0]o, a pronounced in-plane magnetic anisotropy was observed. Soft X-ray magnetic circular dichroism hysteresis loops revealed that for tLSCO ≤ 4 nm, the easy axes for both LSCO and LSMO layers were along the [001]o direction, and the LSCO layer was characterized by magnetically active Co2+ ions that strongly coupled to the LSMO layer. No exchange bias effect was observed in the hysteresis loops. In contrast, along the [11̅0]o direction, the LSCO and LSMO layers displayed a small difference in their coercivity values, and a small exchange bias shift was observed. As tLSCO increased above 4 nm, the easy axis for the LSCO layer remained along the [100]o direction, but it gradually rotated to the [11̅0]o direction for the LSMO layer, resulting in a large negative exchange bias shift. Therefore, we provide a way to control the magnetocrystalline anisotropy and exchange bias by tuning the interfacial exchange coupling between the two FM layers.
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Affiliation(s)
- Mingzhen Feng
- Department
of Materials Science and Engineering, University
of California, Davis, Davis, California 95616, United States
| | - Nolan Ahlm
- Department
of Materials Science and Engineering, University
of California, Davis, Davis, California 95616, United States
| | - Dayne Y. Sasaki
- Department
of Materials Science and Engineering, University
of California, Davis, Davis, California 95616, United States
| | - I-Ting Chiu
- Department
of Chemical Engineering, University of California,
Davis, Davis, California 95616, United States
| | - Alpha T. N’Diaye
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Padraic Shafer
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Christoph Klewe
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Apurva Mehta
- Stanford
Synchrotron Radiation Lightsource, SLAC
National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Yayoi Takamura
- Department
of Materials Science and Engineering, University
of California, Davis, Davis, California 95616, United States
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4
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Xue F, Lin SJ, Song M, Hwang W, Klewe C, Lee CM, Turgut E, Shafer P, Vailionis A, Huang YL, Tsai W, Bao X, Wang SX. Field-free spin-orbit torque switching assisted by in-plane unconventional spin torque in ultrathin [Pt/Co] N. Nat Commun 2023; 14:3932. [PMID: 37402728 DOI: 10.1038/s41467-023-39649-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 06/22/2023] [Indexed: 07/06/2023] Open
Abstract
Electrical manipulation of magnetization without an external magnetic field is critical for the development of advanced non-volatile magnetic-memory technology that can achieve high memory density and low energy consumption. Several recent studies have revealed efficient out-of-plane spin-orbit torques (SOTs) in a variety of materials for field-free type-z SOT switching. Here, we report on the corresponding type-x configuration, showing significant in-plane unconventional spin polarizations from sputtered ultrathin [Pt/Co]N, which are either highly textured on single crystalline MgO substrates or randomly textured on SiO2 coated Si substrates. The unconventional spin currents generated in the low-dimensional Co films result from the strong orbital magnetic moment, which has been observed by X-ray magnetic circular dichroism (XMCD) measurement. The x-polarized spin torque efficiency reaches up to -0.083 and favors complete field-free switching of CoFeB magnetized along the in-plane charge current direction. Micromagnetic simulations additionally demonstrate its lower switching current than type-y switching, especially in narrow current pulses. Our work provides additional pathways for electrical manipulation of spintronic devices in the pursuit of high-speed, high-density, and low-energy non-volatile memory.
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Affiliation(s)
- Fen Xue
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA.
| | - Shy-Jay Lin
- Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
| | - Mingyuan Song
- Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
| | - William Hwang
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Chien-Min Lee
- Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
| | - Emrah Turgut
- Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Arturas Vailionis
- Stanford Nano Shared Facilities, Stanford University, Stanford, CA, 94305, USA
- Department of Physics, Kaunas University of Technology, LT-51368, Kaunas, Lithuania
| | - Yen-Lin Huang
- Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
| | - Wilman Tsai
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Xinyu Bao
- Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
| | - Shan X Wang
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA.
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA.
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5
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McCarter MR, Kim KT, Stoica VA, Das S, Klewe C, Donoway EP, Burn DM, Shafer P, Rodolakis F, Gonçalves MAP, Gómez-Ortiz F, Íñiguez J, García-Fernández P, Junquera J, Lovesey SW, van der Laan G, Park SY, Freeland JW, Martin LW, Lee DR, Ramesh R. Structural Chirality of Polar Skyrmions Probed by Resonant Elastic X-Ray Scattering. Phys Rev Lett 2022; 129:247601. [PMID: 36563236 DOI: 10.1103/physrevlett.129.247601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/08/2022] [Accepted: 10/23/2022] [Indexed: 06/17/2023]
Abstract
An escalating challenge in condensed-matter research is the characterization of emergent order-parameter nanostructures such as ferroelectric and ferromagnetic skyrmions. Their small length scales coupled with complex, three-dimensional polarization or spin structures makes them demanding to trace out fully. Resonant elastic x-ray scattering (REXS) has emerged as a technique to study chirality in spin textures such as skyrmions and domain walls. It has, however, been used to a considerably lesser extent to study analogous features in ferroelectrics. Here, we present a framework for modeling REXS from an arbitrary arrangement of charge quadrupole moments, which can be applied to nanostructures in materials such as ferroelectrics. With this, we demonstrate how extended reciprocal space scans using REXS with circularly polarized x rays can probe the three-dimensional structure and chirality of polar skyrmions. Measurements, bolstered by quantitative scattering calculations, show that polar skyrmions of mixed chirality coexist, and that REXS allows valuation of relative fractions of right- and left-handed skyrmions. Our quantitative analysis of the structure and chirality of polar skyrmions highlights the capability of REXS for establishing complex topological structures toward future application exploits.
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Affiliation(s)
- Margaret R McCarter
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Kook Tae Kim
- Department of Physics, Soongsil University, Seoul 06978, Korea
| | - Vladimir A Stoica
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
- Department of Materials Science and Engineering, Pennsylvania State University, Pennsylvania 16802, USA
| | - Sujit Das
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Elizabeth P Donoway
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - David M Burn
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Fanny Rodolakis
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Mauro A P Gonçalves
- Institute of Physics of the Czech Academy of Sciences, 18221 Prague 8, Czech Republic
| | - Fernando Gómez-Ortiz
- Departmento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, 39005 Santander, Spain
| | - Jorge Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), 5 avenue des Hauts-Fourneaux, L-4362 Esch/Alzette, Luxemburg
- Department of Physics and Materials Science, University of Luxembourg, Rue du Brill 41, L-4422 Belvaux, Luxembourg
| | - Pablo García-Fernández
- Departmento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, 39005 Santander, Spain
| | - Javier Junquera
- Departmento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, 39005 Santander, Spain
| | - Stephen W Lovesey
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
- Department of Physics, Oxford University, Oxford OX1 3PU, United Kingdom
| | - Gerrit van der Laan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Se Young Park
- Department of Physics, Soongsil University, Seoul 06978, Korea
| | - John W Freeland
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Dong Ryeol Lee
- Department of Physics, Soongsil University, Seoul 06978, Korea
| | - Ramamoorthy Ramesh
- Department of Physics, University of California, Berkeley, California 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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6
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Ekanayaka TK, Wang P, Yazdani S, Phillips JP, Mishra E, Dale AS, N'Diaye AT, Klewe C, Shafer P, Freeland J, Streubel R, Wampler JP, Zapf V, Cheng R, Shatruk M, Dowben PA. Evidence of dynamical effects and critical field in a cobalt spin crossover complex. Chem Commun (Camb) 2021; 58:661-664. [PMID: 34914817 DOI: 10.1039/d1cc05309d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The [Co(SQ)2(4-CN-py)2] complex exhibits dynamical effects over a wide range of temperature. The orbital moment, determined by X-ray magnetic circular dichroism (XMCD) with decreasing applied magnetic field, indicates a nonzero critical field for net alignment of magnetic moments, an effect not seen with the spin moment of [Co(SQ)2(4-CN-py)2].
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Affiliation(s)
- Thilini K Ekanayaka
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA.
| | - Ping Wang
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306, USA
| | - Saeed Yazdani
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
| | - Jared Paul Phillips
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
| | - Esha Mishra
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA.
| | - Ashley S Dale
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - John Freeland
- Argonne National Laboratory, Advanced Photon Source, Bldg. 431/E003, 9700 South Cass Ave., Argonne, IL 60439, USA
| | - Robert Streubel
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA. .,Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - James Paris Wampler
- National High Magnetic Field Lab, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA
| | - Vivien Zapf
- National High Magnetic Field Lab, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA
| | - Ruihua Cheng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
| | - Michael Shatruk
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306, USA
| | - Peter A Dowben
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA.
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7
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Da Browski M, Frisk A, Burn DM, Newman DG, Klewe C, N'Diaye AT, Shafer P, Arenholz E, Bowden GJ, Hesjedal T, van der Laan G, Hrkac G, Hicken RJ. Optically and Microwave-Induced Magnetization Precession in [Co/Pt]/NiFe Exchange Springs. ACS Appl Mater Interfaces 2020; 12:52116-52124. [PMID: 33156990 DOI: 10.1021/acsami.0c14058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Microwave and heat-assisted magnetic recordings are two competing technologies that have greatly increased the capacity of hard disk drives. The efficiency of the magnetic recording process can be further improved by employing non-collinear spin structures that combine perpendicular and in-plane magnetic anisotropy. Here, we investigate both microwave and optically excited magnetization dynamics in [Co/Pt]/NiFe exchange spring samples. The resulting canted magnetization within the nanoscale [Co/Pt]/NiFe interfacial region allows for optically stimulated magnetization precession to be observed for an extended magnetic field and frequency range. The results can be explained by formation of an imprinted domain structure, which locks the magnetization orientation and makes the structures more robust against external perturbations. Tuning the canted interfacial domain structure may provide greater control of optically excited magnetization reversal and optically generated spin currents, which are of paramount importance for future ultrafast magnetic recording and spintronic applications.
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Affiliation(s)
- Maciej Da Browski
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, U.K
| | - Andreas Frisk
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K
| | - David M Burn
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K
| | - David G Newman
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, U.K
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Elke Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Cornell High Energy Synchrotron Source, Cornell University, Ithaca, New York 14853, United States
| | - Graham J Bowden
- School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, U.K
| | - Thorsten Hesjedal
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, U.K
| | - Gerrit van der Laan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K
| | - Gino Hrkac
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, U.K
| | - Robert J Hicken
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, U.K
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8
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Emori S, Klewe C, Schmalhorst JM, Krieft J, Shafer P, Lim Y, Smith DA, Sapkota A, Srivastava A, Mewes C, Jiang Z, Khodadadi B, Elmkharram H, Heremans JJ, Arenholz E, Reiss G, Mewes T. Element-Specific Detection of Sub-Nanosecond Spin-Transfer Torque in a Nanomagnet Ensemble. Nano Lett 2020; 20:7828-7834. [PMID: 33084344 DOI: 10.1021/acs.nanolett.0c01868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Spin currents can exert spin-transfer torques on magnetic systems even in the limit of vanishingly small net magnetization, as recently shown for antiferromagnets. Here, we experimentally show that a spin-transfer torque is operative in a macroscopic ensemble of weakly interacting, randomly magnetized Co nanomagnets. We employ element- and time-resolved X-ray ferromagnetic resonance (XFMR) spectroscopy to directly detect subnanosecond dynamics of the Co nanomagnets, excited into precession with cone angle ≳0.003° by an oscillating spin current. XFMR measurements reveal that as the net moment of the ensemble decreases, the strength of the spin-transfer torque increases relative to those of magnetic field torques. Our findings point to spin-transfer torque as an effective way to manipulate the state of nanomagnet ensembles at subnanosecond time scales.
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Affiliation(s)
- Satoru Emori
- Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jan-Michael Schmalhorst
- Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Jan Krieft
- Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Youngmin Lim
- Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - David A Smith
- Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Arjun Sapkota
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Abhishek Srivastava
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Claudia Mewes
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Zijian Jiang
- Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Behrouz Khodadadi
- Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Hesham Elmkharram
- Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Jean J Heremans
- Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Elke Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Cornell High Energy Synchrotron Source, Ithaca, New York 14853, United States
| | - Günter Reiss
- Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Tim Mewes
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, United States
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9
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Yang M, Li Q, Chopdekar RV, Dhall R, Turner J, Carlström JD, Ophus C, Klewe C, Shafer P, N'Diaye AT, Choi JW, Chen G, Wu YZ, Hwang C, Wang F, Qiu ZQ. Creation of skyrmions in van der Waals ferromagnet Fe 3GeTe 2 on (Co/Pd) n superlattice. Sci Adv 2020; 6:6/36/eabb5157. [PMID: 32917619 PMCID: PMC7473669 DOI: 10.1126/sciadv.abb5157] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/15/2020] [Indexed: 05/27/2023]
Abstract
Magnetic skyrmions are topological spin textures, which usually exist in noncentrosymmetric materials where the crystal inversion symmetry breaking generates the so-called Dzyaloshinskii-Moriya interaction. This requirement unfortunately excludes many important magnetic material classes, including the recently found two-dimensional van der Waals (vdW) magnetic materials, which offer unprecedented opportunities for spintronic technology. Using photoemission electron microscopy and Lorentz transmission electron microscopy, we investigated and stabilized Néel-type magnetic skyrmion in vdW ferromagnetic Fe3GeTe2 on top of (Co/Pd) n in which the Fe3GeTe2 has a centrosymmetric crystal structure. We demonstrate that the magnetic coupling between the Fe3GeTe2 and the (Co/Pd) n could create skyrmions in Fe3GeTe2 without the need of an external magnetic field. Our results open exciting opportunities in spintronic research and the engineering of topologically protected nanoscale features by expanding the group of skyrmion host materials to include these previously unknown vdW magnets.
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Affiliation(s)
- M Yang
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - Q Li
- Department of Physics, University of California, Berkeley, CA 94720, USA.
| | - R V Chopdekar
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - R Dhall
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - J Turner
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - J D Carlström
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - C Ophus
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - C Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - P Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - A T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - J W Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - G Chen
- Department of Physics, University of California, Davis, CA 95616, USA
| | - Y Z Wu
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
| | - C Hwang
- Korea Research Institute of Standards and Science, Yuseong, Daejeon 305-340, Republic of Korea
| | - F Wang
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - Z Q Qiu
- Department of Physics, University of California, Berkeley, CA 94720, USA.
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10
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Dąbrowski M, Nakano T, Burn DM, Frisk A, Newman DG, Klewe C, Li Q, Yang M, Shafer P, Arenholz E, Hesjedal T, van der Laan G, Qiu ZQ, Hicken RJ. Coherent Transfer of Spin Angular Momentum by Evanescent Spin Waves within Antiferromagnetic NiO. Phys Rev Lett 2020; 124:217201. [PMID: 32530697 DOI: 10.1103/physrevlett.124.217201] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/06/2020] [Indexed: 06/11/2023]
Abstract
Insulating antiferromagnets have recently emerged as efficient and robust conductors of spin current. Element-specific and phase-resolved x-ray ferromagnetic resonance has been used to probe the injection and transmission of ac spin current through thin epitaxial NiO(001) layers. The spin current is found to be mediated by coherent evanescent spin waves of GHz frequency, rather than propagating magnons of THz frequency, paving the way towards coherent control of the phase and amplitude of spin currents within an antiferromagnetic insulator at room temperature.
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Affiliation(s)
- Maciej Dąbrowski
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, United Kingdom
| | - Takafumi Nakano
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, United Kingdom
- Spintronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan
| | - David M Burn
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - Andreas Frisk
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - David G Newman
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, United Kingdom
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Qian Li
- Department of Physics, University of California at Berkeley, California 94720, USA
| | - Mengmeng Yang
- Department of Physics, University of California at Berkeley, California 94720, USA
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Elke Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Thorsten Hesjedal
- Department of Physics, Clarendon Laboratory, University of Oxford, OX1 Oxford 3PU, United Kingdom
| | - Gerrit van der Laan
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - Zi Q Qiu
- Department of Physics, University of California at Berkeley, California 94720, USA
| | - Robert J Hicken
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, United Kingdom
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11
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Emori S, Yi D, Crossley S, Wisser JJ, Balakrishnan PP, Khodadadi B, Shafer P, Klewe C, N'Diaye AT, Urwin BT, Mahalingam K, Howe BM, Hwang HY, Arenholz E, Suzuki Y. Ultralow Damping in Nanometer-Thick Epitaxial Spinel Ferrite Thin Films. Nano Lett 2018; 18:4273-4278. [PMID: 29792812 DOI: 10.1021/acs.nanolett.8b01261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Pure spin currents, unaccompanied by dissipative charge flow, are essential for realizing energy-efficient nanomagnetic information and communications devices. Thin-film magnetic insulators have been identified as promising materials for spin-current technology because they are thought to exhibit lower damping compared with their metallic counterparts. However, insulating behavior is not a sufficient requirement for low damping, as evidenced by the very limited options for low-damping insulators. Here, we demonstrate a new class of nanometer-thick ultralow-damping insulating thin films based on design criteria that minimize orbital angular momentum and structural disorder. Specifically, we show ultralow damping in <20 nm thick spinel-structure magnesium aluminum ferrite (MAFO), in which magnetization arises from Fe3+ ions with zero orbital angular momentum. These epitaxial MAFO thin films exhibit a Gilbert damping parameter of ∼0.0015 and negligible inhomogeneous linewidth broadening, resulting in narrow half width at half-maximum linewidths of ∼0.6 mT around 10 GHz. Our findings offer an attractive thin-film platform for enabling integrated insulating spintronics.
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Affiliation(s)
- Satoru Emori
- Department of Physics , Virginia Polytechnic Institute and State University , Blacksburg , Virginia 24060 , United States
| | | | | | | | | | - Behrouz Khodadadi
- Department of Physics , Virginia Polytechnic Institute and State University , Blacksburg , Virginia 24060 , United States
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Brittany T Urwin
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | - Krishnamurthy Mahalingam
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | - Brandon M Howe
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | | | - Elke Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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12
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Bougiatioti P, Klewe C, Meier D, Manos O, Kuschel O, Wollschläger J, Bouchenoire L, Brown SD, Schmalhorst JM, Reiss G, Kuschel T. Quantitative Disentanglement of the Spin Seebeck, Proximity-Induced, and Ferromagnetic-Induced Anomalous Nernst Effect in Normal-Metal-Ferromagnet Bilayers. Phys Rev Lett 2017; 119:227205. [PMID: 29286760 DOI: 10.1103/physrevlett.119.227205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Indexed: 06/07/2023]
Abstract
We identify and investigate thermal spin transport phenomena in sputter-deposited Pt/NiFe_{2}O_{x} (4≥x≥0) bilayers. We separate the voltage generated by the spin Seebeck effect from the anomalous Nernst effect (ANE) contributions and even disentangle the ANE in the ferromagnet (FM) from the ANE produced by the Pt that is spin polarized due to its proximity to the FM. Further, we probe the dependence of these effects on the electrical conductivity and the band gap energy of the FM film varying from nearly insulating NiFe_{2}O_{4} to metallic Ni_{33}Fe_{67}. A proximity-induced ANE could only be identified in the metallic Pt/Ni_{33}Fe_{67} bilayer in contrast to Pt/NiFe_{2}O_{x} (x>0) samples. This is verified by the investigation of static magnetic proximity effects via x-ray resonant magnetic reflectivity.
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Affiliation(s)
- Panagiota Bougiatioti
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Christoph Klewe
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Daniel Meier
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Orestis Manos
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Olga Kuschel
- Department of Physics and Center of Physics and Chemistry of New Materials, Osnabrück University, Barbarastrasse 7, 49076 Osnabrück, Germany
| | - Joachim Wollschläger
- Department of Physics and Center of Physics and Chemistry of New Materials, Osnabrück University, Barbarastrasse 7, 49076 Osnabrück, Germany
| | - Laurence Bouchenoire
- XMaS, European Synchrotron Radiation Facility, Grenoble 38043, France
- Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - Simon D Brown
- XMaS, European Synchrotron Radiation Facility, Grenoble 38043, France
- Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - Jan-Michael Schmalhorst
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Günter Reiss
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Timo Kuschel
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
- Physics of Nanodevices, Zernike Institue for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
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13
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Meier D, Reinhardt D, van Straaten M, Klewe C, Althammer M, Schreier M, Goennenwein STB, Gupta A, Schmid M, Back CH, Schmalhorst JM, Kuschel T, Reiss G. Longitudinal spin Seebeck effect contribution in transverse spin Seebeck effect experiments in Pt/YIG and Pt/NFO. Nat Commun 2015; 6:8211. [PMID: 26394541 PMCID: PMC4598359 DOI: 10.1038/ncomms9211] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 07/30/2015] [Indexed: 10/27/2022] Open
Abstract
The spin Seebeck effect, the generation of a spin current by a temperature gradient, has attracted great attention, but the interplay over a millimetre range along a thin ferromagnetic film as well as unintended side effects which hinder an unambiguous detection have evoked controversial discussions. Here, we investigate the inverse spin Hall voltage of a 10 nm thin Pt strip deposited on the magnetic insulators Y3Fe5O12 and NiFe2O4 with a temperature gradient in the film plane. We show characteristics typical of the spin Seebeck effect, although we do not observe the most striking features of the transverse spin Seebeck effect. Instead, we attribute the observed voltages to the longitudinal spin Seebeck effect generated by a contact tip induced parasitic out-of-plane temperature gradient, which depends on material, diameter and temperature of the tip.
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Affiliation(s)
- Daniel Meier
- Department of Physics, Center for Spinelectronic Materials and Devices, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Daniel Reinhardt
- Department of Physics, Center for Spinelectronic Materials and Devices, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Michael van Straaten
- Department of Physics, Center for Spinelectronic Materials and Devices, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Christoph Klewe
- Department of Physics, Center for Spinelectronic Materials and Devices, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Matthias Althammer
- Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner-Strasse 8, 85748 Garching, Germany
| | - Michael Schreier
- Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner-Strasse 8, 85748 Garching, Germany.,Physik-Department, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany
| | - Sebastian T B Goennenwein
- Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner-Strasse 8, 85748 Garching, Germany.,Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany
| | - Arunava Gupta
- Center for Materials for Information Technology, University of Alabama, Tuscaloosa, Alabama 35487, USA
| | - Maximilian Schmid
- Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
| | - Christian H Back
- Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
| | - Jan-Michael Schmalhorst
- Department of Physics, Center for Spinelectronic Materials and Devices, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Timo Kuschel
- Department of Physics, Center for Spinelectronic Materials and Devices, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Günter Reiss
- Department of Physics, Center for Spinelectronic Materials and Devices, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
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14
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Kuschel T, Klewe C, Schmalhorst JM, Bertram F, Kuschel O, Schemme T, Wollschläger J, Francoual S, Strempfer J, Gupta A, Meinert M, Götz G, Meier D, Reiss G. Static Magnetic Proximity Effect in Pt/NiFe2O4 and Pt/Fe Bilayers Investigated by X-Ray Resonant Magnetic Reflectivity. Phys Rev Lett 2015; 115:097401. [PMID: 26371679 DOI: 10.1103/physrevlett.115.097401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Indexed: 06/05/2023]
Abstract
The spin polarization of Pt in Pt/NiFe2O4 and Pt/Fe bilayers is studied by interface-sensitive x-ray resonant magnetic reflectivity to investigate static magnetic proximity effects. The asymmetry ratio of the reflectivity is measured at the Pt L3 absorption edge using circular polarized x-rays for opposite directions of the magnetization at room temperature. The results of the 2% asymmetry ratio for Pt/Fe bilayers are independent of the Pt thickness between 1.8 and 20 nm. By comparison with ab initio calculations, the maximum magnetic moment per spin polarized Pt atom at the interface is determined to be (0.6±0.1) μB for Pt/Fe. For Pt/NiFe2O4 the asymmetry ratio drops below the sensitivity limit of 0.02 μB per Pt atom. Therefore, we conclude, that the longitudinal spin Seebeck effect recently observed in Pt/NiFe2O4 is not influenced by a proximity induced anomalous Nernst effect.
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Affiliation(s)
- T Kuschel
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - C Klewe
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - J-M Schmalhorst
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - F Bertram
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - O Kuschel
- Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49069 Osnabrück, Germany
| | - T Schemme
- Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49069 Osnabrück, Germany
| | - J Wollschläger
- Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49069 Osnabrück, Germany
| | - S Francoual
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - J Strempfer
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - A Gupta
- Center for Materials for Information Technology, University of Alabama, Tuscaloosa, Alabama 35487, USA
| | - M Meinert
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - G Götz
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - D Meier
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - G Reiss
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
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15
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Klewe C, Meinert M, Schmalhorst J, Reiss G. Negative spin polarization of Mn2VGa probed by tunnel magnetoresistance. J Phys Condens Matter 2013; 25:076001. [PMID: 23327939 DOI: 10.1088/0953-8984/25/7/076001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The ferrimagnetic Heusler compound Mn(2)VGa is predicted to have a pseudogap in the majority spin channel, which should lead to a negative tunnel magnetoresistance (TMR). We synthesized epitaxial Mn(2)VGa thin films on MgO(001) substrates by dc and rf magnetron co-sputtering, resulting in nearly stoichiometric films. XRD analysis revealed a mostly B2 ordered structure for the films deposited at substrate temperatures of 350, 450, and 550 °C. Magnetic tunnel junctions with MgO barriers and CoFe counter-electrodes were fabricated. After post-annealing at up to T(a) = 425 °C negative TMR was obtained around zero bias, providing evidence for inverted spin polarization. The band structures of both electrodes were computed within the coherent potential approximation and used to calculate the TMR(V) characteristics, which were in good agreement with our experimental findings.
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Affiliation(s)
- Christoph Klewe
- Department of Physics, Bielefeld University, 33501 Bielefeld, Germany.
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