1
|
Rouzegar R, Wahada MA, Chekhov AL, Hoppe W, Bierhance G, Jechumtál J, Nádvorník L, Wolf M, Seifert TS, Parkin SSP, Woltersdorf G, Brouwer PW, Kampfrath T. Terahertz Spin-Conductance Spectroscopy: Probing Coherent and Incoherent Ultrafast Spin Tunneling. NANO LETTERS 2024; 24:7852-7860. [PMID: 38904438 PMCID: PMC11229073 DOI: 10.1021/acs.nanolett.4c00498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 06/10/2024] [Accepted: 06/11/2024] [Indexed: 06/22/2024]
Abstract
Thin-film stacks F |H consisting of a ferromagnetic-metal layer F and a heavy-metal layer H are spintronic model systems. Here, we present a method to measure the ultrabroadband spin conductance across a layer X between F and H at terahertz frequencies, which are the natural frequencies of spin-transport dynamics. We apply our approach to MgO tunneling barriers with thickness d = 0-6 Å. In the time domain, the spin conductance Gs has two components. An instantaneous feature arises from processes like coherent spin tunneling. Remarkably, a longer-lived component is a hallmark of incoherent resonant spin tunneling mediated by MgO defect states, because its relaxation time grows monotonically with d to as much as 270 fs at d = 6.0 Å. Our results are in full agreement with an analytical model. They indicate that terahertz spin-conductance spectroscopy will yield new and relevant insights into ultrafast spin transport in a wide range of spintronic nanostructures.
Collapse
Affiliation(s)
- Reza Rouzegar
- Department
of Physics, Freie Universität Berlin, 14195 Berlin, Germany
- Department
of Physical Chemistry, Fritz Haber Institute
of the Max Planck Society, 14195 Berlin, Germany
| | - Mohamed Amine Wahada
- Max
Planck Institute for Microstructure Physics, Weinberg 2, 06120 Halle, Germany
- Institut
für Physik, Martin-Luther-Universität
Halle, 06120 Halle, Germany
| | - Alexander L. Chekhov
- Department
of Physics, Freie Universität Berlin, 14195 Berlin, Germany
- Department
of Physical Chemistry, Fritz Haber Institute
of the Max Planck Society, 14195 Berlin, Germany
| | - Wolfgang Hoppe
- Institut
für Physik, Martin-Luther-Universität
Halle, 06120 Halle, Germany
| | - Genaro Bierhance
- Department
of Physics, Freie Universität Berlin, 14195 Berlin, Germany
- Department
of Physical Chemistry, Fritz Haber Institute
of the Max Planck Society, 14195 Berlin, Germany
| | - Jiří Jechumtál
- Faculty
of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague, Czech
Republic
| | - Lukáš Nádvorník
- Faculty
of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague, Czech
Republic
| | - Martin Wolf
- Department
of Physical Chemistry, Fritz Haber Institute
of the Max Planck Society, 14195 Berlin, Germany
| | - Tom S. Seifert
- Department
of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Stuart S. P. Parkin
- Max
Planck Institute for Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Georg Woltersdorf
- Institut
für Physik, Martin-Luther-Universität
Halle, 06120 Halle, Germany
| | - Piet W. Brouwer
- Department
of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Tobias Kampfrath
- Department
of Physics, Freie Universität Berlin, 14195 Berlin, Germany
- Department
of Physical Chemistry, Fritz Haber Institute
of the Max Planck Society, 14195 Berlin, Germany
| |
Collapse
|
2
|
Jin Y, Yu VWZ, Govoni M, Xu AC, Galli G. Excited State Properties of Point Defects in Semiconductors and Insulators Investigated with Time-Dependent Density Functional Theory. J Chem Theory Comput 2023. [PMID: 38039161 DOI: 10.1021/acs.jctc.3c00986] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2023]
Abstract
We present a formulation of spin-conserving and spin-flip hybrid time-dependent density functional theory (TDDFT), including the calculation of analytical forces, which allows for efficient calculations of excited state properties of solid-state systems with hundreds to thousands of atoms. We discuss an implementation on both GPU- and CPU-based architectures along with several acceleration techniques. We then apply our formulation to the study of several point defects in semiconductors and insulators, specifically the negatively charged nitrogen-vacancy and neutral silicon-vacancy centers in diamond, the neutral divacancy center in 4H silicon carbide, and the neutral oxygen-vacancy center in magnesium oxide. Our results highlight the importance of taking into account structural relaxations in excited states in order to interpret and predict optical absorption and emission mechanisms in spin defects.
Collapse
Affiliation(s)
- Yu Jin
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Victor Wen-Zhe Yu
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Marco Govoni
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Physics, Computer Science, and Mathematics, University of Modena and Reggio Emilia, Modena 41125, Italy
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Andrew C Xu
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Giulia Galli
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| |
Collapse
|
3
|
Liu Q, Liu P, Li X, Hu S, Zhu Y, Jin C, Han W, Ji Y, Xu Z, Hu S, Ye M, Chen L. Perpendicular Manganite Magnetic Tunnel Junctions Induced by Interfacial Coupling. ACS APPLIED MATERIALS & INTERFACES 2022; 14:13883-13890. [PMID: 35274527 DOI: 10.1021/acsami.1c24146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The half-metallic manganite oxide La2/3Sr1/3MnO3 (LSMO) has a very high spin polarization of ∼100%, making it ideal for ferromagnetic electrodes to realize tunneling magnetoresistance (TMR). Because of the in-plane magnetic anisotropy of the ferromagnetic LSMO electrode, which leads to the density limit of memory, realizing perpendicular tunneling in manganite-based magnetic tunnel junctions (MTJ) is critical for future applications. Here, we design and fabricate manganite-based MTJs composed of alternately stacked cobaltite and manganite layers that demonstrate strong perpendicular magnetic anisotropy (PMA) induced by interfacial coupling. Moreover, spin-dependent tunneling behaviors with an out-of-plane magnetic field were observed in the perpendicular MTJs. We found that the direct tunneling effect plays a dominant role in the low bias region during the transport behavior of devices, which is associated with thermionic emission of electrons or oxygen vacancies in the high bias region. Our works of realizing perpendicular tunneling in manganite-based MTJs lead to new approaches for designing and developing all-oxide spintronic devices.
Collapse
Affiliation(s)
- Qi Liu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Pengfei Liu
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Xiaowen Li
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Sixia Hu
- Materials Characterization and Preparation Center, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yuanmin Zhu
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan 523808, China
| | - Cai Jin
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Wenqiao Han
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yanjiang Ji
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zedong Xu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- School of Electronics and Information Engineering, Tiangong University, Tianjin 300387, China
| | - Songbai Hu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Mao Ye
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Lang Chen
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Materials Characterization and Preparation Center, Southern University of Science and Technology, Shenzhen 518055, China
| |
Collapse
|
4
|
Liu Q, Miao J, Reeve R, Meng KK, Xu XG, Wu Y, Jiang Y. Ultra-large non-volatile modulation of magnetic moments in PbZr 0.2Ti 0.8O 3/MgO/La 0.7Sr 0.3MnO 3 heterostructure at room temperature via interfacial polarization mediation. Sci Rep 2017; 7:2627. [PMID: 28572679 PMCID: PMC5453987 DOI: 10.1038/s41598-017-03019-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 04/21/2017] [Indexed: 12/03/2022] Open
Abstract
Multiferroic hybrid structures PbZr0.2Ti0.8O3 (PZT)/La0.7Sr0.3MnO3 (LSMO) and PZT/MgO/LSMO were epitaxially deposited on (001) Nb:SrTiO3 crystals. Crystallinity and ferroelectric domain structures were investigated for the PZT/LSMO heterostructure. Interestingly, relatively high non-volatile magnetoelectric coupling effects were observed in both heterostructures at room temperature. The change of chemical valence for Mn and Ti at the PZT/MgO/LSMO interface may play a dominant role rather than external strain or orbital reconstruction, which lead to a large modulation of the magnetization. Correspondingly, the transport behavior of the PZT/MgO/LSMO heterostructure is investigated to confirm the role of oxygen vacancies motion. Our result indicates that the PZT/MgO/LSMO heterostructure have a promising application for future high-density non-volatile memories.
Collapse
Affiliation(s)
- Q Liu
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - J Miao
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Robert Reeve
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
| | - K K Meng
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - X G Xu
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Y Wu
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Y Jiang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
| |
Collapse
|
5
|
Coherent ultrafast spin-dynamics probed in three dimensional topological insulators. Sci Rep 2015; 5:15304. [PMID: 26510509 PMCID: PMC4625143 DOI: 10.1038/srep15304] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/11/2015] [Indexed: 11/24/2022] Open
Abstract
Topological insulators are candidates to open up a novel route in spin based electronics. Different to traditional ferromagnetic materials, where the carrier spin-polarization and magnetization are based on the exchange interaction, the spin properties in topological insulators are based on the coupling of spin- and orbit interaction connected to its momentum. Specific ways to control the spin-polarization with light have been demonstrated: the energy momentum landscape of the Dirac cone provides spin-momentum locking of the charge current and its spin. We investigate a spin-related signal present only during the laser excitation studying real and imaginary part of the complex Kerr angle by disentangling spin and lattice contributions. This coherent signal is only present at the time of the pump-pulses’ light field and can be described in terms of a Raman coherence time. The Raman transition involves states at the bottom edge of the conduction band. We demonstrate a coherent femtosecond control of spin-polarization for electronic states at around the Dirac cone.
Collapse
|
6
|
Schleicher F, Halisdemir U, Lacour D, Gallart M, Boukari S, Schmerber G, Davesne V, Panissod P, Halley D, Majjad H, Henry Y, Leconte B, Boulard A, Spor D, Beyer N, Kieber C, Sternitzky E, Cregut O, Ziegler M, Montaigne F, Beaurepaire E, Gilliot P, Hehn M, Bowen M. Localized states in advanced dielectrics from the vantage of spin- and symmetry-polarized tunnelling across MgO. Nat Commun 2014; 5:4547. [DOI: 10.1038/ncomms5547] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 06/27/2014] [Indexed: 11/09/2022] Open
|
7
|
Dey P, Weber W. Electron-spin motion: a new tool to study ferromagnetic films and surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:473201. [PMID: 22075703 DOI: 10.1088/0953-8984/23/47/473201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
When electrons are interacting with a ferromagnetic material, their spin-polarization vector is expected to move. This spin motion, comprising an azimuthal precession and a polar rotation about the magnetization direction of the ferromagnet, has been studied in spin-polarized electron scattering experiments both in transmission and reflection geometry. In this review we show that electron-spin motion can be considered as a new tool to study ferromagnetic films and surfaces and we discuss its application to a number of different problems: (a) the transmission of spin-polarized electrons across ferromagnetic films, (b) the influence of spin-dependent gaps in the electronic band structure on the spin motion in reflection geometry, (c) interference experiments with spin-polarized electrons and (d) the influence of lattice relaxations in ferromagnetic films on the spin motion.
Collapse
Affiliation(s)
- P Dey
- Institut de Physique et Chimie des Matériaux de Strasbourg, UDS-CNRS, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| | | |
Collapse
|
8
|
Jia X, Xia K, Bauer GEW. Thermal spin transfer in Fe-MgO-Fe tunnel junctions. PHYSICAL REVIEW LETTERS 2011; 107:176603. [PMID: 22107551 DOI: 10.1103/physrevlett.107.176603] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Indexed: 05/31/2023]
Abstract
We compute thermal spin transfer (TST) torques in Fe-MgO-Fe tunnel junctions using a first principles wave-function-matching method. At room temperature, the TST in a junction with 3 MgO monolayers amounts to 10(-7) J/m(2)/K, which is estimated to cause magnetization reversal for temperature differences over the barrier of the order of 10 K. The large TST can be explained by multiple scattering between interface states through ultrathin barriers. The angular dependence of the TST can be very skewed, possibly leading to thermally induced high-frequency generation.
Collapse
Affiliation(s)
- Xingtao Jia
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | | | | |
Collapse
|
9
|
Teixeira JM, Ventura J, Araujo JP, Sousa JB, Wisniowski P, Cardoso S, Freitas PP. Resonant tunneling through electronic trapping states in thin MgO magnetic junctions. PHYSICAL REVIEW LETTERS 2011; 106:196601. [PMID: 21668184 DOI: 10.1103/physrevlett.106.196601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Indexed: 05/30/2023]
Abstract
We report an inelastic electron tunneling spectroscopy study on MgO magnetic junctions with thin barriers (0.85-1.35 nm). Inelastic electron tunneling spectroscopy reveals resonant electronic trapping within the barrier for voltages V>0.15 V. These trapping features are associated with defects in the barrier crystalline structure, as confirmed by high-resolution transmission electron microscopy. Such defects are responsible for resonant tunneling due to energy levels that are formed in the barrier. A model was applied to determine the average location and energy level of the traps, indicating that they are mostly located in the middle of the MgO barrier, in accordance with the high-resolution transmission electron microscopy data and trap-assisted tunneling conductance theory. Evidence of the influence of trapping on the voltage dependence of tunnel magnetoresistance is shown.
Collapse
Affiliation(s)
- J M Teixeira
- IFIMUP and IN-Institute of Nanoscience and Nanotechnology, and Departamento de Fisica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.
| | | | | | | | | | | | | |
Collapse
|
10
|
Park YJ, Hickey MC, Van Veenhuizen MJ, Chang J, Heiman D, Perry CH, Moodera JS. Efficient spin transfer phenomena in Fe/MgO/GaAs structure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:116002. [PMID: 21358034 DOI: 10.1088/0953-8984/23/11/116002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The efficiency of spin polarized charge transfer was investigated in an Fe/MgO tunnel barrier/GaAs based structure using spin dependent photocurrent measurements, whereby a spin imbalance in carrier population was generated in the GaAs by circularly polarized light. The dominance of tunneling transport processes over Schottky emission gave rise to a high spin transfer efficiency of 35% under the photovoltaic mode of device operation. A spin dependent tunneling conductance associated with spin polarized electron transport was identified by the observation of phase changes. This transport prevails over the unpolarized electron and hole conduction over the bias range which corresponds to flat band conditions.
Collapse
Affiliation(s)
- Y J Park
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | | | | | | | | | | | | |
Collapse
|
11
|
Ke Y, Xia K, Guo H. Oxygen-vacancy-induced diffusive scattering in Fe/MgO/Fe magnetic tunnel junctions. PHYSICAL REVIEW LETTERS 2010; 105:236801. [PMID: 21231491 DOI: 10.1103/physrevlett.105.236801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 10/03/2010] [Indexed: 05/30/2023]
Abstract
By first principles analysis, we systematically investigate effects of oxygen vacancies (OV) in the MgO barrier of Fe/MgO/Fe magnetic tunnel junctions. The interchannel diffusive scattering by disordered OVs located at or near the Fe/MgO interface drastically reduces the tunnel magnetoresistance ratio (TMR) from the ideal theoretical limit to the presently observed much smaller experimental range. Interior OVs are far less important in influencing TMR, but they significantly increase the junction resistance. Filling OV with nitrogen atoms restores TMR to near the ideal theoretical limit.
Collapse
Affiliation(s)
- Youqi Ke
- Centre for the Physics of Materials and Department of Physics, McGill University, Montreal, PQ H3A 2T8, Canada
| | | | | |
Collapse
|
12
|
Lu Y, Tran M, Jaffrès H, Seneor P, Deranlot C, Petroff F, George JM, Lépine B, Ababou S, Jézéquel G. Spin-polarized inelastic tunneling through insulating barriers. PHYSICAL REVIEW LETTERS 2009; 102:176801. [PMID: 19518806 DOI: 10.1103/physrevlett.102.176801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Indexed: 05/27/2023]
Abstract
Spin-conserving hopping transport through chains of localized states has been evidenced by taking benefit of the high degree of spin-polarization of CoFeB-MgO-CoFeB magnetic tunnel junctions. In particular, our data show that relatively thick MgO barriers doped with boron favor the activation of spin-conserving inelastic channels through a chain of three localized states and leading to reduced magnetoresistance effects. We propose an extension of the Glazman-Matveev theory to the case of ferromagnetic reservoirs to account for spin-polarized inelastic tunneling through nonmagnetic localized states embedded in an insulating barrier.
Collapse
Affiliation(s)
- Y Lu
- Unité Mixte de Physique CNRS/Thales, Campus Polytechnique, 1 Avenue Augustin Fresnel, 91767 Palaiseau Cedex and Université Paris-Sud 11, 91405, Orsay, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Miao GX, Ramos AV, Moodera JS. Infinite magnetoresistance from the spin dependent proximity effect in symmetry driven bcc-Fe/V/Fe heteroepitaxial superconducting spin valves. PHYSICAL REVIEW LETTERS 2008; 101:137001. [PMID: 18851482 DOI: 10.1103/physrevlett.101.137001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Indexed: 05/26/2023]
Abstract
Superconductivity in fully epitaxial bcc-Fe/V/Fe hybrid spin valve structures is influenced by the spin currents and supercurrents as well as band symmetry. The transition temperature is spin dependent in the presence of the proximity effect. A unique feature in this system is the band symmetry filtering taking place at the Fe/V interface. The absence of Delta2 Bloch states at the Fermi level in the Fe spin majority channel leads to spin selectivity and reduced transparency at the interface. Infinite magnetoresistance with clear remanence states is obtained, and implies the potential for spintronic applications.
Collapse
Affiliation(s)
- Guo-Xing Miao
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
| | | | | |
Collapse
|