1
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Kamashev AA, Garif’yanov NN, Validov AA, Kataev V, Osin AS, Fominov YV, Garifullin IA. Superconducting spin valve effect in Co/Pb/Co heterostructures with insulating interlayers. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2024; 15:457-464. [PMID: 38711583 PMCID: PMC11070957 DOI: 10.3762/bjnano.15.41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 04/09/2024] [Indexed: 05/08/2024]
Abstract
We report the superconducting properties of Co/Pb/Co heterostructures with thin insulating interlayers. The main specific feature of these structures is the intentional oxidation of both superconductor/ferromagnet (S/F) interfaces. We study the variation of the critical temperature of our systems due to switching between parallel and antiparallel configurations of the magnetizations of the two magnetic layers. Common knowledge suggests that this spin valve effect, which is due to the S/F proximity effect, is most pronounced in the case of perfect metallic contacts at the interfaces. Nevertheless, in our structures with intentionally deteriorated interfaces, we observed a significant full spin valve effect. A shift of the superconducting transition temperature Tc by switching the mutual orientation of the magnetizations of the two ferromagnetic Co layers from antiparallel to parallel amounted to ΔTc = 0.2 K at the optimal thickness of the superconducting Pb layer. Our findings verify the so far unconfirmed earlier results by Deutscher and Meunier on an F1/S/F2 heterostructure with oxidized interlayers [Deutscher, G.; Meunier, F. Phys. Rev. Lett. 1969, 22, 395. https://doi.org/10.1103/PhysRevLett.22.395] and suggest an alternative route to optimize the performance of superconducting spin valves.
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Affiliation(s)
- Andrey A Kamashev
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of RAS, 420029 Kazan, Russia
| | - Nadir N Garif’yanov
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of RAS, 420029 Kazan, Russia
| | - Aidar A Validov
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of RAS, 420029 Kazan, Russia
| | - Vladislav Kataev
- Leibniz Institute for Solid State and Materials Research, Helmholtzstr. 20, D-01069 Dresden, Germany
| | - Alexander S Osin
- L. D. Landau Institute for Theoretical Physics RAS, 142432 Chernogolovka, Russia
| | - Yakov V Fominov
- L. D. Landau Institute for Theoretical Physics RAS, 142432 Chernogolovka, Russia
- Laboratory for Condensed Matter Physics, HSE University, 101000 Moscow, Russia
| | - Ilgiz A Garifullin
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of RAS, 420029 Kazan, Russia
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2
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Sanchez JJ, Fabbris G, Choi Y, DeStefano JM, Rosenberg E, Shi Y, Malinowski P, Huang Y, Mazin II, Kim JW, Chu JH, Ryan PJ. Strain-switchable field-induced superconductivity. SCIENCE ADVANCES 2023; 9:eadj5200. [PMID: 38000034 PMCID: PMC10672156 DOI: 10.1126/sciadv.adj5200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/26/2023] [Indexed: 11/26/2023]
Abstract
Field-induced superconductivity is a rare phenomenon where an applied magnetic field enhances or induces superconductivity. Here, we use applied stress as a control switch between a field-tunable superconducting state and a robust non-field-tunable state. This marks the first demonstration of a strain-tunable superconducting spin valve with infinite magnetoresistance. We combine tunable uniaxial stress and applied magnetic field on the ferromagnetic superconductor Eu(Fe0.88Co0.12)2As2 to shift the field-induced zero-resistance temperature between 4 K and a record-high value of 10 K. We use x-ray diffraction and spectroscopy measurements under stress and field to reveal that strain tuning of the nematic order and field tuning of the ferromagnetism act as independent control parameters of the superconductivity. Combining comprehensive measurements with DFT calculations, we propose that field-induced superconductivity arises from a novel mechanism, namely, the uniquely dominant effect of the Eu dipolar field when the exchange field splitting is nearly zero.
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Affiliation(s)
- Joshua J. Sanchez
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Gilberto Fabbris
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | | | - Elliott Rosenberg
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Yue Shi
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Paul Malinowski
- Department of Physics, University of Washington, Seattle, WA 98195, USA
- Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - Yina Huang
- Department of Physics, Zhejiang University of Science and Technology, Hangzhou 310023, People’s Republic of China
| | - Igor I. Mazin
- Department of Physics and Astronomy and Quantum Science and Engineering Center, George Mason University, Fairfax, VA 22030, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Jiun-Haw Chu
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Philip J. Ryan
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
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3
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Jo J, Peisen Y, Yang H, Mañas-Valero S, Baldoví JJ, Lu Y, Coronado E, Casanova F, Bergeret FS, Gobbi M, Hueso LE. Local control of superconductivity in a NbSe 2/CrSBr van der Waals heterostructure. Nat Commun 2023; 14:7253. [PMID: 37945570 PMCID: PMC10636142 DOI: 10.1038/s41467-023-43111-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 10/31/2023] [Indexed: 11/12/2023] Open
Abstract
Two-dimensional magnets and superconductors are emerging as tunable building-blocks for quantum computing and superconducting spintronic devices, and have been used to fabricate all two-dimensional versions of traditional devices, such as Josephson junctions. However, novel devices enabled by unique features of two-dimensional materials have not yet been demonstrated. Here, we present NbSe2/CrSBr van der Waals superconducting spin valves that exhibit infinite magnetoresistance and nonreciprocal charge transport. These responses arise from a unique metamagnetic transition in CrSBr, which controls the presence of localized stray fields suitably oriented to suppress the NbSe2 superconductivity in nanoscale regions and to break time reversal symmetry. Moreover, by integrating different CrSBr crystals in a lateral heterostructure, we demonstrate a superconductive spin valve characterized by multiple stable resistance states. Our results show how the unique physical properties of layered materials enable the realization of high-performance quantum devices based on novel working principles.
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Affiliation(s)
- Junhyeon Jo
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain.
| | - Yuan Peisen
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain
| | - Haozhe Yang
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain
| | - Samuel Mañas-Valero
- Instituto de Ciencia Molecular (ICMol), Universitat de València, Paterna, Spain
| | - José J Baldoví
- Instituto de Ciencia Molecular (ICMol), Universitat de València, Paterna, Spain
| | - Yao Lu
- Centro de Física de Materiales (CFM-MPC) Centro Mixto CSIC-UPV/EHU, Donostia-San Sebastian, Spain
| | - Eugenio Coronado
- Instituto de Ciencia Molecular (ICMol), Universitat de València, Paterna, Spain
| | - Fèlix Casanova
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - F Sebastian Bergeret
- Centro de Física de Materiales (CFM-MPC) Centro Mixto CSIC-UPV/EHU, Donostia-San Sebastian, Spain
- Donostia International Physics Center (DIPC), E-20018, Donostia-San Sebastián, Spain
| | - Marco Gobbi
- Centro de Física de Materiales (CFM-MPC) Centro Mixto CSIC-UPV/EHU, Donostia-San Sebastian, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
| | - Luis E Hueso
- CIC nanoGUNE BRTA, Donostia-San Sebastian, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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4
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Narita H, Ishizuka J, Kan D, Shimakawa Y, Yanase Y, Ono T. Magnetization Control of Zero-Field Intrinsic Superconducting Diode Effect. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2304083. [PMID: 37410358 DOI: 10.1002/adma.202304083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/28/2023] [Accepted: 07/03/2023] [Indexed: 07/07/2023]
Abstract
The superconducting diode effect (SDE), which causes a superconducting state in one direction and a normal-conducting state in another, has significant potential for developing ultralow power consumption circuits and non-volatile memory. However, the practical control of the SDE necessities the precise tuning of current, temperature, magnetic field, or magnetism. Therefore, the mechanisms of the SDE must be understood to develop novel materials and devices capable of realizing the SDE under more controlled and robust conditions. This study demonstrates an intrinsic zero-field SDE with an efficiency of up to 40% in Fe/Pt-inserted non-centrosymmetric Nb/V/Ta superconducting artificial superlattices. The polarity and magnitude of the zero-field SDE are controllable by the direction of magnetization, indicating that the effective exchange field acts on Cooper pairs. Furthermore, the first-principles calculation indicates that the SDE can be enhanced by an asymmetric configuration of proximity induced magnetic moments in superconducting layers, which induces a magnetic toroidal moment. This study has important implications regarding the development of novel materials and devices that can effectively control the SDE. Moreover, the magnetization control of the SDE is expected to aid in the designing of superconducting quantum devices and establishing a material platform for topological superconductors.
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Affiliation(s)
- Hideki Narita
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
| | - Jun Ishizuka
- Faculty of Engineering, Niigata University, Ikarashi, Niigata, 950-2181, Japan
| | - Daisuke Kan
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
- Center for Spintronics Research Network, Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Yuichi Shimakawa
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
- Center for Spintronics Research Network, Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Youichi Yanase
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
- Institute for Molecular Science, Okazaki, 444-0867, Japan
| | - Teruo Ono
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
- Center for Spintronics Research Network, Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
- Center for Spintronics Research Network, Graduate School of Engineering Science, Osaka University, Toyonaka, 560-0043, Japan
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5
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Zhang B, Yun C, Wu H, Zhao Z, Zeng Y, Liang D, Shen T, Zhang J, Huang X, Song J, Xu J, Zhang Q, Tan PH, Gao S, Hou Y. Two-Dimensional Wedge-Shaped Magnetic EuS: Insight into the Substrate Step-Guided Epitaxial Synthesis on Sapphire. J Am Chem Soc 2022; 144:19758-19769. [PMID: 36257067 DOI: 10.1021/jacs.2c06023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rare earth chalcogenides (RECs) with novel luminescence and magnetic properties offer fascinating opportunities for fundamental research and applications. However, controllable synthesis of RECs down to the two-dimensional (2D) limit still has a great challenge. Herein, 2D wedge-shaped ferromagnetic EuS single crystals are successfully synthesized via a facile molten-salt-assisted chemical vapor deposition method on sapphire. Based on the theoretical simulations and experimental measurements, the mechanisms of aligned growth and wedge-shaped growth are systematically proposed. The wedge-shaped growth is driven by a dual-interaction mechanism, where the coupling between EuS and the substrate steps impedes the lateral growth, and the strong bonding of nonlayered EuS itself facilitates the vertical growth. Through temperature-dependent Raman and photoluminescence characterization, the nanoflakes show a large Raman temperature coefficient of -0.030 cm-1 K-1 and uncommon increasing band gap with temperature. More importantly, by low-temperature magnetic force microscopy characterization, thickness variation of the magnetic signal is revealed within one sample, indicating the great potential of the wedge-shaped nanoflake to serve as a platform for highly efficient investigation of thickness-dependent magnetic properties. This work sheds new light on 2D RECs and will offer a deep understanding of 2D wedge-shaped materials.
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Affiliation(s)
- Biao Zhang
- School of Materials Science and Engineering, Peking University, Beijing100871, China.,Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing Innovation Center for Engineering Science and Advanced Technology, Peking University, Beijing100871, China
| | - Chao Yun
- State Key Laboratory for Mesoscopic Physics, School of Physics, Beijing Key Laboratory for Magnetoeletric Materials and Devices, Peking University, Beijing100871, China
| | - Heng Wu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing100083, China
| | - Zijing Zhao
- School of Materials Science and Engineering, Peking University, Beijing100871, China.,Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing Innovation Center for Engineering Science and Advanced Technology, Peking University, Beijing100871, China
| | - Yi Zeng
- School of Materials Science and Engineering, Peking University, Beijing100871, China.,Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing Innovation Center for Engineering Science and Advanced Technology, Peking University, Beijing100871, China
| | - Dong Liang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Beijing Key Laboratory for Magnetoeletric Materials and Devices, Peking University, Beijing100871, China
| | - Tong Shen
- School of Materials Science and Engineering, Peking University, Beijing100871, China.,Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing Innovation Center for Engineering Science and Advanced Technology, Peking University, Beijing100871, China
| | - Jine Zhang
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing100191, China
| | - Xiaoxiao Huang
- School of Materials Science and Engineering, Peking University, Beijing100871, China.,Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing Innovation Center for Engineering Science and Advanced Technology, Peking University, Beijing100871, China
| | - Jiepeng Song
- School of Materials Science and Engineering, Peking University, Beijing100871, China
| | - Junjie Xu
- School of Materials Science and Engineering, Peking University, Beijing100871, China.,Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing Innovation Center for Engineering Science and Advanced Technology, Peking University, Beijing100871, China
| | - Qing Zhang
- School of Materials Science and Engineering, Peking University, Beijing100871, China
| | - Ping-Heng Tan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing100083, China
| | - Song Gao
- Institute of Spin-X Science and Technology, South China University of Technology, Guangzhou510641, China
| | - Yanglong Hou
- School of Materials Science and Engineering, Peking University, Beijing100871, China.,Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing Innovation Center for Engineering Science and Advanced Technology, Peking University, Beijing100871, China
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6
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Narita H, Ishizuka J, Kawarazaki R, Kan D, Shiota Y, Moriyama T, Shimakawa Y, Ognev AV, Samardak AS, Yanase Y, Ono T. Field-free superconducting diode effect in noncentrosymmetric superconductor/ferromagnet multilayers. NATURE NANOTECHNOLOGY 2022; 17:823-828. [PMID: 35773423 DOI: 10.1038/s41565-022-01159-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 05/23/2022] [Indexed: 06/15/2023]
Abstract
The diode effect is fundamental to electronic devices and is widely used in rectifiers and a.c.-d.c. converters. At low temperatures, however, conventional semiconductor diodes possess a high resistivity, which yields energy loss and heating during operation. The superconducting diode effect (SDE)1-8, which relies on broken inversion symmetry in a superconductor, may mitigate this obstacle: in one direction, a zero-resistance supercurrent can flow through the diode, but for the opposite direction of current flow, the device enters the normal state with ohmic resistance. The application of a magnetic field can induce SDE in Nb/V/Ta superlattices with a polar structure1,2, in superconducting devices with asymmetric patterning of pinning centres9 or in superconductor/ferromagnet hybrid devices with induced vortices10,11. The need for an external magnetic field limits their practical application. Recently, a field-free SDE was observed in a NbSe2/Nb3Br8/NbSe2 junction; it originates from asymmetric Josephson tunnelling that is induced by the Nb3Br8 barrier and the associated NbSe2/Nb3Br8 interfaces12. Here, we present another implementation of zero-field SDE using noncentrosymmetric [Nb/V/Co/V/Ta]20 multilayers. The magnetic layers provide the necessary symmetry breaking, and we can tune the SDE by adjusting the structural parameters, such as the constituent elements, film thickness, stacking order and number of repetitions. We control the polarity of the SDE through the magnetization direction of the ferromagnetic layers. Artificially stacked structures13-18, such as the one used in this work, are of particular interest as they are compatible with microfabrication techniques and can be integrated with devices such as Josephson junctions19-22. Energy-loss-free SDEs as presented in this work may therefore enable novel non-volatile memories and logic circuits with ultralow power consumption.
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Affiliation(s)
- Hideki Narita
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, Japan.
| | - Jun Ishizuka
- Institute for Theoretical Physics, ETH Zurich, Zurich, Switzerland
| | - Ryo Kawarazaki
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, Japan
| | - Daisuke Kan
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, Japan
- Center for Spintronics Research Network, Institute for Chemical Research, Kyoto University, Uji, Japan
| | - Yoichi Shiota
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, Japan
- Center for Spintronics Research Network, Institute for Chemical Research, Kyoto University, Uji, Japan
| | - Takahiro Moriyama
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, Japan
- Center for Spintronics Research Network, Institute for Chemical Research, Kyoto University, Uji, Japan
| | - Yuichi Shimakawa
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, Japan
- Center for Spintronics Research Network, Institute for Chemical Research, Kyoto University, Uji, Japan
| | - Alexey V Ognev
- Laboratory of Spin-Orbitronics, Institute of High Technologies and Advanced Materials, Far Eastern Federal University, Vladivostok, Russia
| | - Alexander S Samardak
- Laboratory of Spin-Orbitronics, Institute of High Technologies and Advanced Materials, Far Eastern Federal University, Vladivostok, Russia
| | - Youichi Yanase
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan
- Institute for Molecular Science, Okazaki, Japan
| | - Teruo Ono
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, Japan.
- Center for Spintronics Research Network, Institute for Chemical Research, Kyoto University, Uji, Japan.
- Laboratory of Spin-Orbitronics, Institute of High Technologies and Advanced Materials, Far Eastern Federal University, Vladivostok, Russia.
- Center for Spintronics Research Network, Graduate School of Engineering Science, Osaka University, Toyonaka, Japan.
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7
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Machon P, Wolf MJ, Beckmann D, Belzig W. Experimental and theoretical study of field-dependent spin splitting at ferromagnetic insulator-superconductor interfaces. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2022; 13:682-688. [PMID: 35957675 PMCID: PMC9344541 DOI: 10.3762/bjnano.13.60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
We present a combined experimental and theoretical work that investigates the magnetic proximity effect at a ferromagnetic insulator-superconductor (FI-S) interface. The calculations are based on the boundary condition for diffusive quasiclassical Green's functions, which accounts for arbitrarily strong spin-dependent effects and spin mixing angles. The resulting phase diagram shows a transition from a first-order to a second-order phase transition for large spin mixing angles. The experimentally found differential conductance of an EuS-Al heterostructure is compared with the theoretical calculation. With the assumption of a uniform spin mixing angle that depends on the externally applied field, we find good agreement between theory and experiment. The theory depends only on very few parameters, mostly specified by the experimental setup. We determine the effective spin of the interface moments as J ≈ 0.74ℏ.
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Affiliation(s)
- Peter Machon
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
| | - Michael J Wolf
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), D-76021 Karlsruhe, Germany
- present address: Institute for Technical Physics, Karlsruhe Institute of Technology (KIT), D-76021 Karlsruhe, Germany
| | - Detlef Beckmann
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology (KIT), D-76021 Karlsruhe, Germany
| | - Wolfgang Belzig
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
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8
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Choi E, Sim KI, Burch KS, Lee YH. Emergent Multifunctional Magnetic Proximity in van der Waals Layered Heterostructures. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200186. [PMID: 35596612 PMCID: PMC9313546 DOI: 10.1002/advs.202200186] [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: 01/11/2022] [Revised: 04/01/2022] [Indexed: 05/10/2023]
Abstract
Proximity effect, which is the coupling between distinct order parameters across interfaces of heterostructures, has attracted immense interest owing to the customizable multifunctionalities of diverse 3D materials. This facilitates various physical phenomena, such as spin order, charge transfer, spin torque, spin density wave, spin current, skyrmions, and Majorana fermions. These exotic physics play important roles for future spintronic applications. Nevertheless, several fundamental challenges remain for effective applications: unavoidable disorder and lattice mismatch limits in the growth process, short characteristic length of proximity, magnetic fluctuation in ultrathin films, and relatively weak spin-orbit coupling (SOC). Meanwhile, the extensive library of atomically thin, 2D van der Waals (vdW) layered materials, with unique characteristics such as strong SOC, magnetic anisotropy, and ultraclean surfaces, offers many opportunities to tailor versatile and more effective functionalities through proximity effects. Here, this paper focuses on magnetic proximity, i.e., proximitized magnetism and reviews the engineering of magnetism-related functionalities in 2D vdW layered heterostructures for next-generation electronic and spintronic devices. The essential factors of magnetism and interfacial engineering induced by magnetic layers are studied. The current limitations and future challenges associated with magnetic proximity-related physics phenomena in 2D heterostructures are further discussed.
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Affiliation(s)
- Eun‐Mi Choi
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS)Sungkyunkwan University (SKKU)Suwon16419Republic of Korea
| | - Kyung Ik Sim
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS)Sungkyunkwan University (SKKU)Suwon16419Republic of Korea
| | - Kenneth S. Burch
- Department of PhysicsBoston College140 Commonwealth AveChestnut HillMA02467‐3804USA
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS)Sungkyunkwan University (SKKU)Suwon16419Republic of Korea
- Department of Energy ScienceSungkyunkwan UniversitySuwon16419Republic of Korea
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9
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Ojajärvi R, Bergeret FS, Silaev MA, Heikkilä TT. Dynamics of Two Ferromagnetic Insulators Coupled by Superconducting Spin Current. PHYSICAL REVIEW LETTERS 2022; 128:167701. [PMID: 35522505 DOI: 10.1103/physrevlett.128.167701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 03/21/2022] [Indexed: 06/14/2023]
Abstract
A conventional superconductor sandwiched between two ferromagnets can maintain coherent equilibrium spin current. This spin supercurrent results from the rotation of odd-frequency spin correlations induced in the superconductor by the magnetic proximity effect. In the absence of intrinsic magnetization, the superconductor cannot maintain multiple rotations of the triplet component but instead provides a Josephson type weak link for the spin supercurrent. We determine the analog of the current-phase relation in various circumstances and show how it can be accessed in experiments on dynamic magnetization. In particular, concentrating on the magnetic hysteresis and the ferromagnetic resonance response, we show how the spin supercurrent affects the nonequilibrium dynamics of magnetization which depends on a competition between spin supercurrent mediated static exchange contribution and a dynamic spin pumping contribution. Depending on the outcome of this competition, a mode crossing in the system can either be an avoided crossing or mode locking.
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Affiliation(s)
- Risto Ojajärvi
- Department of Physics and Nanoscience Center, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä, Finland
| | - F S Bergeret
- Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
- Donostia International Physics Center (DIPC), Manuel de Lardizabal 4, E-20018 San Sebastián, Spain
| | - M A Silaev
- Department of Physics and Nanoscience Center, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä, Finland
- Computational Physics Laboratory, Physics Unit, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 692, FI-33720 Tampere, Finland
| | - Tero T Heikkilä
- Department of Physics and Nanoscience Center, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä, Finland
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10
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Neto JF, Silva CCDS. Mesoscale Phase Separation of Skyrmion-Vortex Matter in Chiral-Magnet-Superconductor Heterostructures. PHYSICAL REVIEW LETTERS 2022; 128:057001. [PMID: 35179935 DOI: 10.1103/physrevlett.128.057001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 08/05/2021] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
We investigate theoretically the equilibrium configurations of many magnetic skyrmions interacting with many superconducting vortices in a superconductor-chiral-magnet bilayer. We show that miscible mixtures of vortices and skyrmions in this system break down at a particular wave number for sufficiently strong coupling, giving place to remarkably diverse mesoscale patterns: gel, stripes, clusters, intercalated stripes, and composite gel-cluster structures. We also demonstrate that, by appropriate choice of parameters, one can thermally tune between the homogeneous and density-modulated phases.
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Affiliation(s)
- José F Neto
- Departamento de Física, Universidade Federal de Pernambuco, Cidade Universitária, 50670-901 Recife-PE, Brazil
| | - Clécio C de Souza Silva
- Departamento de Física, Universidade Federal de Pernambuco, Cidade Universitária, 50670-901 Recife-PE, Brazil
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11
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Gomez-Perez JM, Zhang XP, Calavalle F, Ilyn M, González-Orellana C, Gobbi M, Rogero C, Chuvilin A, Golovach VN, Hueso LE, Bergeret FS, Casanova F. Strong Interfacial Exchange Field in a Heavy Metal/Ferromagnetic Insulator System Determined by Spin Hall Magnetoresistance. NANO LETTERS 2020; 20:6815-6823. [PMID: 32786952 DOI: 10.1021/acs.nanolett.0c02834] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Spin-dependent transport at heavy metal/magnetic insulator interfaces is at the origin of many phenomena at the forefront of spintronics research. A proper quantification of the different interfacial spin conductances is crucial for many applications. Here, we report the first measurement of the spin Hall magnetoresistance (SMR) of Pt on a purely ferromagnetic insulator (EuS). We perform SMR measurements in a wide range of temperatures and fit the results by using a microscopic model. From this fitting procedure, we obtain the temperature dependence of the spin conductances (Gs, Gr, and Gi), disentangling the contribution of field-like torque (Gi), damping-like torque (Gr), and spin-flip scattering (Gs). An interfacial exchange field of the order of 1 meV acting upon the conduction electrons of Pt can be estimated from Gi, which is at least three times larger than Gr below the Curie temperature. Our work provides an easy method to quantify this interfacial spin-splitting field, which plays a key role in emerging fields such as superconducting spintronics and caloritronics as well as topological quantum computation.
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Affiliation(s)
| | - Xian-Peng Zhang
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Basque Country, Spain
- Centro de Fı́sica de Materiales CFM-MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastian, Basque Country, Spain
| | | | - Maxim Ilyn
- Centro de Fı́sica de Materiales CFM-MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastian, Basque Country, Spain
| | - Carmen González-Orellana
- Centro de Fı́sica de Materiales CFM-MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastian, Basque Country, Spain
| | - Marco Gobbi
- CIC nanoGUNE BRTA, 20018 Donostia-San Sebastian, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Basque Country, Spain
- Centro de Fı́sica de Materiales CFM-MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastian, Basque Country, Spain
| | - Celia Rogero
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Basque Country, Spain
- Centro de Fı́sica de Materiales CFM-MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastian, Basque Country, Spain
| | - Andrey Chuvilin
- CIC nanoGUNE BRTA, 20018 Donostia-San Sebastian, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Basque Country, Spain
| | - Vitaly N Golovach
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Basque Country, Spain
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Basque Country, Spain
- Centro de Fı́sica de Materiales CFM-MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastian, Basque Country, Spain
- Departamento de Física de Materiales UPV/EHU, 20018 Donostia-San Sebastian, Basque Country, Spain
| | - Luis E Hueso
- CIC nanoGUNE BRTA, 20018 Donostia-San Sebastian, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Basque Country, Spain
| | - F Sebastian Bergeret
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Basque Country, Spain
- Centro de Fı́sica de Materiales CFM-MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastian, Basque Country, Spain
| | - Fèlix Casanova
- CIC nanoGUNE BRTA, 20018 Donostia-San Sebastian, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Basque Country, Spain
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12
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Li Z, Zhang X, Zhao X, Li J, Herng TS, Xu H, Lin F, Lyu P, Peng X, Yu W, Hai X, Chen C, Yang H, Martin J, Lu J, Luo X, Castro Neto AH, Pennycook SJ, Ding J, Feng Y, Lu J. Imprinting Ferromagnetism and Superconductivity in Single Atomic Layers of Molecular Superlattices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1907645. [PMID: 32419256 DOI: 10.1002/adma.201907645] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 04/08/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
Ferromagnetism and superconductivity are two antagonistic phenomena since ferromagnetic exchange fields tend to destroy singlet Cooper pairs. Reconciliation of these two competing phases has been achieved in vertically stacked heterostructures where these two orders are confined in different layers. However, controllable integration of these two phases in one atomic layer is a longstanding challenge. Here, an interlayer-space-confined chemical design (ICCD) is reported for the synthesis of dilute single-atom-doped TaS2 molecular superlattice, whereby ferromagnetism is observed in the superconducting TaS2 layers. The intercalation of 2H-TaS2 crystal with bulky organic ammonium molecule expands its van der Waals gap for single-atom doping via co-intercalated cobalt ions, resulting in the formation of quasi-monolayer Co-doped TaS2 superlattices. Isolated Co atoms are decorated in the basal plane of the TaS2 via substituting the Ta atom or anchoring at a hollow site, wherein the orbital-selected p-d hybridization between Co and neighboring Ta and S atoms induces local magnetic moments with strong ferromagnetic coupling. This ICCD approach can be applied to various metal ions, enabling the synthesis of a series of crystal-size TaS2 molecular superlattices.
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Affiliation(s)
- Zejun Li
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Xiuying Zhang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore
- State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing, 100871, P. R. China
| | - Xiaoxu Zhao
- Department of Materials Science & Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Jing Li
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Tun Seng Herng
- Department of Materials Science & Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Haomin Xu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Fanrong Lin
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Pin Lyu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Xinnan Peng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Wei Yu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Xiao Hai
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Cheng Chen
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Huimin Yang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Jens Martin
- Institut für Kristallzüchtung, Max-Born-Str. 2, Berlin, 12489, Germany
| | - Jing Lu
- State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing, 100871, P. R. China
| | - Xin Luo
- School of Physics, Sun Yat-sen University, Guangzhou, 510275, P. R. China
| | - A H Castro Neto
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Stephen J Pennycook
- Department of Materials Science & Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Jun Ding
- Department of Materials Science & Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Yuanping Feng
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore
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13
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Manna S, Wei P, Xie Y, Law KT, Lee PA, Moodera JS. Signature of a pair of Majorana zero modes in superconducting gold surface states. Proc Natl Acad Sci U S A 2020; 117:8775-8782. [PMID: 32253317 PMCID: PMC7183215 DOI: 10.1073/pnas.1919753117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Under certain conditions, a fermion in a superconductor can separate in space into two parts known as Majorana zero modes, which are immune to decoherence from local noise sources and are attractive building blocks for quantum computers. Promising experimental progress has been made to demonstrate Majorana zero modes in materials with strong spin-orbit coupling proximity coupled to superconductors. Here we report signatures of Majorana zero modes in a material platform utilizing the surface states of gold. Using scanning tunneling microscope to probe EuS islands grown on top of gold nanowires, we observe two well-separated zero-bias tunneling conductance peaks aligned along the direction of the applied magnetic field, as expected for a pair of Majorana zero modes. This platform has the advantage of having a robust energy scale and the possibility of realizing complex designs using lithographic methods.
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Affiliation(s)
- Sujit Manna
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Physics, Indian Institute of Technology Delhi, 110 016 New Delhi, India
| | - Peng Wei
- Department of Physics and Astronomy, University of California, Riverside, CA 92521;
| | - Yingming Xie
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong
| | - Kam Tuen Law
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong
| | - Patrick A Lee
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139;
| | - Jagadeesh S Moodera
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139;
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139
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14
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Di Bernardo A, Komori S, Livanas G, Divitini G, Gentile P, Cuoco M, Robinson JWA. Nodal superconducting exchange coupling. NATURE MATERIALS 2019; 18:1194-1200. [PMID: 31527810 DOI: 10.1038/s41563-019-0476-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 08/06/2019] [Indexed: 06/10/2023]
Abstract
A superconducting spin valve consists of a thin-film superconductor between two ferromagnetic layers. A change of magnetization alignment shifts the superconducting transition temperature (ΔΤc) due to an interplay between the magnetic exchange energy and the superconducting condensate. The magnitude of ΔΤc scales inversely with the superconductor thickness (dS) and is zero when dS exceeds the superconducting coherence length (ξ). Here, we report a superconducting spin-valve effect involving a different underlying mechanism in which magnetization alignment and ΔΤc are determined by nodal quasiparticle excitation states on the Fermi surface of the d-wave superconductor YBa2Cu3O7-δ sandwiched between insulating layers of ferromagnetic Pr0.8Ca0.2MnO3. We observe ΔΤc values that approach 2 K with the sign of ΔΤc oscillating with dS over a length scale exceeding 100ξ and, for particular values of dS, the superconducting state reinforces an antiparallel magnetization alignment. These results pave the way to all-oxide superconducting memory in which superconductivity modulates the magnetic state.
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Affiliation(s)
- A Di Bernardo
- Department of Materials Science & Metallurgy, University of Cambridge, Cambridge, UK.
- University of Konstanz, Konstanz, Germany.
| | - S Komori
- Department of Materials Science & Metallurgy, University of Cambridge, Cambridge, UK
| | - G Livanas
- CNR-SPIN, c/o University of Salerno, Fisciano, Salerno, Italy
| | - G Divitini
- Department of Materials Science & Metallurgy, University of Cambridge, Cambridge, UK
| | - P Gentile
- CNR-SPIN, c/o University of Salerno, Fisciano, Salerno, Italy
| | - M Cuoco
- CNR-SPIN, c/o University of Salerno, Fisciano, Salerno, Italy
| | - J W A Robinson
- Department of Materials Science & Metallurgy, University of Cambridge, Cambridge, UK.
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15
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Kaminaga K, Oka D, Oka H, Fukumura T. Heteroepitaxy of Rock-salt Superconductor/Ferromagnet Thin Film: LaO/EuO. CHEM LETT 2019. [DOI: 10.1246/cl.190460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Kenichi Kaminaga
- WPI-Advanced Institute for Materials Research and Core Research Cluster, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Daichi Oka
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Hirofumi Oka
- WPI-Advanced Institute for Materials Research and Core Research Cluster, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Tomoteru Fukumura
- WPI-Advanced Institute for Materials Research and Core Research Cluster, Tohoku University, Sendai, Miyagi 980-8577, Japan
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
- Center for Science and Innovation in Spintronics, Organization for Advanced Studies, Tohoku University, Sendai, Miyagi 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai, Miyagi 980-8577, Japan
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16
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Wei P, Manna S, Eich M, Lee P, Moodera J. Superconductivity in the Surface State of Noble Metal Gold and its Fermi Level Tuning by EuS Dielectric. PHYSICAL REVIEW LETTERS 2019; 122:247002. [PMID: 31322391 DOI: 10.1103/physrevlett.122.247002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/27/2019] [Indexed: 06/10/2023]
Abstract
The induced superconductivity (SC) in a robust and scalable quantum material with strong Rashba spin-orbit coupling is particularly attractive for generating topological superconductivity and Majorana bound states (MBS). Gold (111) thin film has been proposed as a promising candidate because of the large Rashba energy, the predicted topological nature, and the possibility for large-scale MBS device fabrications. We experimentally demonstrate two important steps towards achieving such a goal. We successfully show induced SC in the Shockley surface state (SS) of ultrathin Au(111) layers grown over epitaxial vanadium films, which is easily achievable on a wafer scale. The emergence of SC in the SS, which is physically separated from a bulk superconductor, is attained by indirect quasiparticle scattering processes instead of by conventional interfacial Andreev reflections. We further show the ability to tune the SS Fermi level (E_{F}) by interfacing SS with a high-κ dielectric ferromagnetic insulator EuS. The shift of E_{F} from ∼550 to ∼34 mV in superconducting SS is an important step towards realizing MBS in this robust system.
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Affiliation(s)
- Peng Wei
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Sujit Manna
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Marius Eich
- Plasma Science and Fusion Center & Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland
| | - Patrick Lee
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jagadeesh Moodera
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Plasma Science and Fusion Center & Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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17
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De Simoni G, Strambini E, Moodera JS, Bergeret FS, Giazotto F. Toward the Absolute Spin-Valve Effect in Superconducting Tunnel Junctions. NANO LETTERS 2018; 18:6369-6374. [PMID: 30248266 DOI: 10.1021/acs.nanolett.8b02723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A superconductor with a spin-split excitation spectrum behaves as an ideal ferromagnetic spin-injector in a tunneling junction. It was theoretically predicted that the combination of two such spin-split superconductors with independently tunable magnetizations may be used as an ideal absolute spin-valve. Here, we report on the first switchable superconducting spin-valve based on two EuS/Al bilayers coupled through an aluminum oxide tunnel barrier. The spin-valve shows a relative resistance change between the parallel and antiparallel configuration of the EuS layers up to 900% that demonstrates a highly spin-polarized current through the junction. Our device may be pivotal for realization of thermoelectric radiation detectors, a logical element for a memory cell in cryogenics, superconductor-based computers, and superconducting spintronics in general.
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Affiliation(s)
- Giorgio De Simoni
- NEST Istituto Nanoscienze-CNR and Scuola Normale Superiore , I-56127 Pisa , Italy
| | - Elia Strambini
- NEST Istituto Nanoscienze-CNR and Scuola Normale Superiore , I-56127 Pisa , Italy
| | - Jagadeesh S Moodera
- Department of Physics, Francis Bitter Magnet Lab and Plasma Science and Fusion Center , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - F Sebastian Bergeret
- Centro de Fisica de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU , Manuel de Lardizabal 5 , E-20018 San Sebastian , Spain
- Donostia International Physics Center (DIPC) , Manuel de Lardizabal 4 , E-20018 San Sebastian , Spain
| | - Francesco Giazotto
- NEST Istituto Nanoscienze-CNR and Scuola Normale Superiore , I-56127 Pisa , Italy
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18
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Komori S, Di Bernardo A, Buzdin AI, Blamire MG, Robinson JWA. Magnetic Exchange Fields and Domain Wall Superconductivity at an All-Oxide Superconductor-Ferromagnet Insulator Interface. PHYSICAL REVIEW LETTERS 2018; 121:077003. [PMID: 30169105 DOI: 10.1103/physrevlett.121.077003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/20/2018] [Indexed: 06/08/2023]
Abstract
At a superconductor-ferromagnet (S/F) interface, the F layer can introduce a magnetic exchange field within the S layer, which acts to locally spin split the superconducting density of states. The effect of magnetic exchange fields on superconductivity has been thoroughly explored at S-ferromagnet insulator (S/FI) interfaces for isotropic s-wave S and a thickness that is smaller than the superconducting coherence length. Here we report a magnetic exchange field effect at an all-oxide S/FI interface involving the anisotropic d-wave high temperature superconductor praseodymium cerium copper oxide (PCCO) and the FI praseodymium calcium manganese oxide (PCMO). The magnetic exchange field in PCCO, detected via magnetotransport measurements through the superconducting transition, is localized to the PCCO/PCMO interface with an average magnitude that depends on the presence or absence of magnetic domain walls in PCMO. The results are promising for the development of all-oxide superconducting spintronic devices involving unconventional pairing and high temperature superconductors.
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Affiliation(s)
- S Komori
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - A Di Bernardo
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - A I Buzdin
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
- University Bordeaux, LOMA UMR-CNRS 5798, F-33405 Talence Cedex, France
| | - M G Blamire
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - J W A Robinson
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
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19
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Cardoso C, Soriano D, García-Martínez NA, Fernández-Rossier J. Van der Waals Spin Valves. PHYSICAL REVIEW LETTERS 2018; 121:067701. [PMID: 30141640 DOI: 10.1103/physrevlett.121.067701] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Indexed: 05/22/2023]
Abstract
We propose spin valves where a 2D nonmagnetic conductor is intercalated between two ferromagnetic insulating layers. In this setup, the relative orientation of the magnetizations of the insulating layers can have a strong impact on the in-plane conductivity of the 2D conductor. We first show this for a graphene bilayer, described with a tight-binding model, placed between two ferromagnetic insulators. In the antiparallel configuration, a band gap opens at the Dirac point, whereas in the parallel configuration, the graphene bilayer remains conducting. We then compute the electronic structure of graphene bilayer placed between two monolayers of the ferromagnetic insulator CrI_{3}, using density functional theory. Consistent with the model, we find that a gap opens at the Dirac point only in the antiparallel configuration.
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Affiliation(s)
- C Cardoso
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - D Soriano
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - N A García-Martínez
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - J Fernández-Rossier
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-330 Braga, Portugal
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20
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Birge NO. Spin-triplet supercurrents in Josephson junctions containing strong ferromagnetic materials. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:20150150. [PMID: 29941625 PMCID: PMC6030151 DOI: 10.1098/rsta.2015.0150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/28/2015] [Indexed: 06/08/2023]
Abstract
The proximity effect between a superconducting material and a non-superconducting normal metal can extend over distances of the order of micrometres at sufficiently low temperatures. If the normal metal is replaced by a ferromagnetic material, the spatial extent of the proximity effect drops precipitously due to the exchange splitting between the majority and minority spin bands in the ferromagnet. In 2001, several theorists predicted that spin-triplet pair correlations could be induced in proximity systems involving multiple ferromagnetic materials (or multiple domains in one material) with non-collinear magnetizations. Such spin-triplet pair correlations should extend deep into the ferromagnet, producing a long-range proximity effect. In this paper, we review our experimental work in this area, which has focused primarily on Josephson junctions containing strong ferromagnetic materials. We show that Josephson junctions containing particular combinations of strong ferromagnetic materials can carry spin-triplet supercurrent over distances of at least several tens of nanometres, whereas spin-singlet supercurrent in similar samples decays over a length scale of about 1 nm. We also mention important work by other groups; however, this article is not intended to be a review of the whole field.This article is part of the theme issue 'Andreev bound states'.
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Affiliation(s)
- Norman O Birge
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
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21
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Li Z, Zhao Y, Mu K, Shan H, Guo Y, Wu J, Su Y, Wu Q, Sun Z, Zhao A, Cui X, Wu C, Xie Y. Molecule-Confined Engineering toward Superconductivity and Ferromagnetism in Two-Dimensional Superlattice. J Am Chem Soc 2017; 139:16398-16404. [DOI: 10.1021/jacs.7b10071] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zejun Li
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Yingcheng Zhao
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Kejun Mu
- National
Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People’s Republic of China
| | - Huan Shan
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Yuqiao Guo
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Jiajing Wu
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Yueqi Su
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Qiran Wu
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Zhe Sun
- National
Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People’s Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People’s Republic of China
| | - Aidi Zhao
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Xuefeng Cui
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Changzheng Wu
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Yi Xie
- Hefei
National Laboratory for Physical Sciences at the Microscale, CAS Center
for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical
Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
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22
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Zhu Y, Pal A, Blamire MG, Barber ZH. Superconducting exchange coupling between ferromagnets. NATURE MATERIALS 2017; 16:195-199. [PMID: 27643729 DOI: 10.1038/nmat4753] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 08/15/2016] [Indexed: 05/14/2023]
Abstract
Recent discoveries from superconductor (S)/ferromagnet (FM) heterostructures include π-junctions, triplet pairing, critical temperature (Tc) control in FM/S/FM superconducting spin valves (SSVs) and critical current control in S/FM/N/FM/S spin valve Josephson junctions (N: normal metal). In all cases, the magnetic state of the device, generally set by the applied field, controls the superconducting response. We report here the observation of the converse effect, that is, direct superconducting control of the magnetic state in GdN/Nb/GdN SSVs. A model for an antiferromagnetic effective exchange interaction based on the coupling of the superconducting condensation energy to the magnetic state can explain the Nb thickness and temperature dependence of this effect. This superconducting exchange interaction is fundamentally different in origin from the various exchange coupling phenomena that underlie conventional spin electronics (spintronics), and provides a mechanism for the active control of the magnetic state in superconducting spintronics.
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Affiliation(s)
- Yi Zhu
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
| | - Avradeep Pal
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
| | - Mark G Blamire
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
| | - Zoe H Barber
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
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23
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Wei P, Lee S, Lemaitre F, Pinel L, Cutaia D, Cha W, Katmis F, Zhu Y, Heiman D, Hone J, Moodera JS, Chen CT. Strong interfacial exchange field in the graphene/EuS heterostructure. NATURE MATERIALS 2016; 15:711-6. [PMID: 27019382 DOI: 10.1038/nmat4603] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/22/2016] [Indexed: 05/20/2023]
Abstract
Exploiting 2D materials for spintronic applications can potentially realize next-generation devices featuring low power consumption and quantum operation capability. The magnetic exchange field (MEF) induced by an adjacent magnetic insulator enables efficient control of local spin generation and spin modulation in 2D devices without compromising the delicate material structures. Using graphene as a prototypical 2D system, we demonstrate that its coupling to the model magnetic insulator (EuS) produces a substantial MEF (>14 T) with the potential to reach hundreds of tesla, which leads to orders-of-magnitude enhancement of the spin signal originating from the Zeeman spin Hall effect. Furthermore, the new ferromagnetic ground state of Dirac electrons resulting from the strong MEF may give rise to quantized spin-polarized edge transport. The MEF effect shown in our graphene/EuS devices therefore provides a key functionality for future spin logic and memory devices based on emerging 2D materials in classical and quantum information processing.
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Affiliation(s)
- Peng Wei
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Sunwoo Lee
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA
- Electrical Engineering Department, Columbia University, New York, New York 10027, USA
| | - Florian Lemaitre
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA
- Institut polytechnique de Grenoble, F38031 Grenoble Cedex 1, France
| | - Lucas Pinel
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA
- Institut polytechnique de Grenoble, F38031 Grenoble Cedex 1, France
| | - Davide Cutaia
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA
- IBM Zurich Research Laboratory, Säumerstrasse 4, CH- 8803 Rüschlikon, Switzerland
| | - Wujoon Cha
- Mechanical Engineering Department, Columbia University, New York, New York 10027, USA
| | - Ferhat Katmis
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Yu Zhu
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Donald Heiman
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - James Hone
- Mechanical Engineering Department, Columbia University, New York, New York 10027, USA
| | - Jagadeesh S Moodera
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Ching-Tzu Chen
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA
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24
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Wei P, Katmis F, Chang CZ, Moodera JS. Induced Superconductivity and Engineered Josephson Tunneling Devices in Epitaxial (111)-Oriented Gold/Vanadium Heterostructures. NANO LETTERS 2016; 16:2714-2719. [PMID: 26943807 DOI: 10.1021/acs.nanolett.6b00361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report a unique experimental approach to create topological superconductors by inducing superconductivity into epitaxial metallic thin film with strong spin-orbit coupling. Utilizing molecular beam epitaxy technique under ultrahigh vacuum conditions, we are able to achieve (111) oriented single phase of gold (Au) thin film grown on a well-oriented vanadium (V) s-wave superconductor film with clean interface. We obtained atomically smooth Au thin films with thicknesses even down to below a nanometer showing near-ideal surface quality. The as-grown V/Au bilayer heterostructure exhibits superconducting transition at around 3.9 K. Clear Josephson tunneling and Andreev reflection are observed in S-I-S tunnel junctions fabricated from the epitaxial bilayers. The barrier thickness dependent tunneling and the associated subharmonic gap structures (SGS) confirmed the induced superconductivity in Au (111), paving the way for engineering thin film heterostructures based on p-wave superconductivity and nano devices exploiting Majorana Fermions for quantum computing.
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Affiliation(s)
- Peng Wei
- Francis Bitter Magnet Laboratory, ‡Department of Physics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Ferhat Katmis
- Francis Bitter Magnet Laboratory, ‡Department of Physics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Cui-Zu Chang
- Francis Bitter Magnet Laboratory, ‡Department of Physics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Jagadeesh S Moodera
- Francis Bitter Magnet Laboratory, ‡Department of Physics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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25
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Jacobsen SH, Kulagina I, Linder J. Controlling superconducting spin flow with spin-flip immunity using a single homogeneous ferromagnet. Sci Rep 2016; 6:23926. [PMID: 27045733 PMCID: PMC4820725 DOI: 10.1038/srep23926] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 03/15/2016] [Indexed: 11/08/2022] Open
Abstract
Spin transport via electrons is typically plagued by Joule heating and short decay lengths due to spin-flip scattering. It is known that dissipationless spin currents can arise when using conventional superconducting contacts, yet this has only been experimentally demonstrated when using intricate magnetically inhomogeneous multilayers, or in extreme cases such as half-metals with interfacial magnetic disorder. Moreover, it is unknown how such spin supercurrents decay in the presence of spin-flip scattering. Here, we present a method for generating a spin supercurrent by using only a single homogeneous magnetic element. Remarkably, the spin supercurrent generated in this way does not decay spatially, in stark contrast to normal spin currents that remain polarized only up to the spin relaxation length. We also expose the existence of a superconductivity-mediated torque even without magnetic inhomogeneities, showing that the different components of the spin supercurrent polarization respond fundamentally differently to a change in the superconducting phase difference. This establishes a mechanism for tuning dissipationless spin and charge flow separately, and confirms the advantage that superconductors can offer in spintronics.
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Affiliation(s)
- Sol H. Jacobsen
- Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Iryna Kulagina
- Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Jacob Linder
- Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
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26
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Gu Y, Halász GB, Robinson JWA, Blamire MG. Large Superconducting Spin Valve Effect and Ultrasmall Exchange Splitting in Epitaxial Rare-Earth-Niobium Trilayers. PHYSICAL REVIEW LETTERS 2015; 115:067201. [PMID: 26296128 DOI: 10.1103/physrevlett.115.067201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Indexed: 06/04/2023]
Abstract
Epitaxial Ho/Nb/Ho and Dy/Nb/Dy superconducting spin valves show a reversible change in the zero-field critical temperature (ΔT(c0)) of ∼400 mK and an infinite magnetoresistance on changing the relative magnetization of the Ho or Dy layers. Unlike transition-metal superconducting spin valves, which show much smaller ΔT(c0) values, our results can be quantitatively modeled. However, the fits require an extraordinarily low induced exchange splitting which is dramatically lower than known values for rare-earth Fermi-level electrons, implying that new models for the magnetic proximity effect may be required.
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Affiliation(s)
- Yuanzhou Gu
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Gábor B Halász
- Theoretical Physics, Oxford University, 1 Keble Road, Oxford OX1 3NP, United Kingdom
| | - J W A Robinson
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - M G Blamire
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
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27
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Giazotto F, Heikkilä TT, Bergeret FS. Very large thermophase in ferromagnetic Josephson junctions. PHYSICAL REVIEW LETTERS 2015; 114:067001. [PMID: 25723238 DOI: 10.1103/physrevlett.114.067001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Indexed: 06/04/2023]
Abstract
The concept of thermophase refers to the appearance of a phase gradient inside a superconductor originating from the presence of an applied temperature bias across it. The resulting supercurrent flow may, in suitable conditions, fully counterbalance the temperature-bias-induced quasiparticle current therefore preventing the formation of any voltage drop, i.e., a thermovoltage, across the superconductor. Yet, the appearance of a thermophase is expected to occur in Josephson-coupled superconductors as well. Here, we theoretically investigate the thermoelectric response of a thermally biased Josephson junction based on a ferromagnetic insulator. In particular, we predict the occurrence of a very large thermophase that can reach π/2 across the contact for suitable temperatures and structure parameters; i.e., the quasiparticle thermal current can reach the critical current. Such a thermophase can be several orders of magnitude larger than that predicted to occur in conventional Josephson tunnel junctions. In order to assess experimentally the predicted very large thermophase, we propose a realistic setup realizable with state-of-the-art nanofabrication techniques and well-established materials, based on a superconducting quantum interference device. This effect could be of strong relevance in several low-temperature applications, for example, for revealing tiny temperature differences generated by coupling the electromagnetic radiation to one of the superconductors forming the junction.
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Affiliation(s)
- F Giazotto
- NEST, Instituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa, Italy
| | - T T Heikkilä
- Department of Physics and Nanoscience Center, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä, Finland and Low Temperature Laboratory, Aalto University, P.O. Box 15100, FI-00076 AALTO, Finland
| | - F S Bergeret
- Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, Manuel de Lardizabal 4, E-20018 San Sebastián, Spain and Donostia International Physics Center (DIPC), Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
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28
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Miao GX, Moodera JS. Spin manipulation with magnetic semiconductor barriers. Phys Chem Chem Phys 2015; 17:751-61. [DOI: 10.1039/c4cp04599h] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Magnetic semiconductors with unique spin-filtering property and the ability to create excessive internal magnetic fields can open myriads of new phenomena.
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Affiliation(s)
- Guo-Xing Miao
- Institute for Quantum
- Computing and Department of Electrical and Computer Engineering
- University of Waterloo
- Waterloo
- Canada
| | - Jagadeesh S. Moodera
- Francis Bitter Magnet Laboratory
- Massachusetts Institute of Technology
- Cambridge
- USA
- Department of Physics
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29
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Ozaeta A, Virtanen P, Bergeret FS, Heikkilä TT. Predicted very large thermoelectric effect in ferromagnet-superconductor junctions in the presence of a spin-splitting magnetic field. PHYSICAL REVIEW LETTERS 2014; 112:057001. [PMID: 24580623 DOI: 10.1103/physrevlett.112.057001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Indexed: 06/03/2023]
Abstract
We show that a huge thermoelectric effect can be observed by contacting a superconductor whose density of states is spin split by a Zeeman field with a ferromagnet with a nonzero polarization. The resulting thermopower exceeds kB/e by a large factor, and the thermoelectric figure of merit ZT can far exceed unity, leading to heat engine efficiencies close to the Carnot limit. We also show that spin-polarized currents can be generated in the superconductor by applying a temperature bias.
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Affiliation(s)
- A Ozaeta
- Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
| | - P Virtanen
- Low Temperature Laboratory, Aalto University, P.O. Box 15100, FI-00076 Aalto, Finland
| | - F S Bergeret
- Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, Manuel de Lardizabal 5, E-20018 San Sebastián, Spain and Donostia International Physics Center (DIPC), Manuel de Lardizabal 5, E-20018 San Sebastián, Spain and Institut für Physik, Carl von Ossietzky Universität, D-26111 Oldenburg, Germany
| | - T T Heikkilä
- Low Temperature Laboratory, Aalto University, P.O. Box 15100, FI-00076 Aalto, Finland and Nanoscience Center, Department of Physics, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä, Jyväskylä, Finland
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