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Simon C, Silevitch D, Stamp P, Rosenbaum T. Quantum Barkhausen noise induced by domain wall cotunneling. Proc Natl Acad Sci U S A 2024; 121:e2315598121. [PMID: 38502694 PMCID: PMC10990130 DOI: 10.1073/pnas.2315598121] [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: 09/07/2023] [Accepted: 02/14/2024] [Indexed: 03/21/2024] Open
Abstract
Most macroscopic magnetic phenomena (including magnetic hysteresis) are typically understood classically. Here, we examine the dynamics of a uniaxial rare-earth ferromagnet deep within the quantum regime, so that domain wall motion, and the associated hysteresis, is initiated by quantum nucleation, which then grows into large-scale domain wall motion, which is observable as an unusual form of Barkhausen noise. We observe noncritical behavior in the resulting avalanche dynamics that only can be explained by going beyond traditional renormalization group methods or classical domain wall models. We find that this "quantum Barkhausen noise" exhibits two distinct mechanisms for domain wall movement, each of which is quantum-mechanical, but with very different dependences on an external magnetic field applied transverse to the spin (Ising) axis. These observations can be understood in terms of the correlated motion of pairs of domain walls, nucleated by cotunneling of plaquettes (sections of domain wall), with plaquette pairs correlated by dipolar interactions; this correlation is suppressed by the transverse field. Similar macroscopic correlations may be expected to appear in the hysteresis of other systems with long-range interactions.
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Affiliation(s)
- C. Simon
- Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA91125
| | - D.M. Silevitch
- Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA91125
| | - P.C.E. Stamp
- Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA91125
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BCV6T 1Z1, Canada
- Pacific Institute of Theoretical Physics, University of British Columbia, Vancouver, BCV6T 1Z1, Canada
| | - T.F. Rosenbaum
- Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA91125
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Hurst HM, Galitski V, Heikkilä TT. Electron Induced Massive Dynamics of Magnetic Domain Walls. PHYSICAL REVIEW. B 2020; 101:10.1103/physrevb.101.054407. [PMID: 38567107 PMCID: PMC10986426 DOI: 10.1103/physrevb.101.054407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
We study the dynamics of domain walls (DWs) in a metallic, ferromagnetic nanowire, focusing on inertial effects on the DW due to interaction with a conduction electron bath. We develop a Keldysh collective coordinate technique to describe the effect of conduction electrons on rigid magnetic structures. The effective Lagrangian and Langevin equations of motion for a DW are derived microscopically, including the full response kernel which is nonlocal in time. The DW dynamics is described by two collective degrees of freedom: position and tilt-angle. The coupled Langevin equations therefore involve two correlated noise sources, leading to a generalized fluctuation-dissipation theorem (FDT). The DW response kernel due to electrons contains two parts: one related to dissipation via FDT, and another reactive part. We prove that the latter term leads to a mass for both degrees of freedom, even though the intrinsic bare mass is zero. The electron-induced mass is present even in a clean system without pinning or specifically engineered potentials. The resulting equations of motion contain rich dynamical solutions and point toward a way to control domain wall motion in metals via the electronic system properties. We discuss two observable consequences of the mass, hysteresis in the DW dynamics and resonant response to ac current.
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Affiliation(s)
- Hilary M Hurst
- Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, Maryland, 20899, USA
- Department of Physics and Astronomy, San José State University, San José, California, 95192, USA
| | - Victor Galitski
- Joint Quantum Institute and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
| | - 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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Wang D, Dong Y, Yan Z, Wang XG, He J, Guo GH. Domain wall motion driven by adiabatic spin transfer torque through excitation of nonlinear dynamics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:206005. [PMID: 27124892 DOI: 10.1088/0953-8984/28/20/206005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Domain wall dynamics under the joint action of a linearly polarized microwave magnetic field and spin transfer torque was analysed in terms of the domain wall collective coordinates. It was found that a microwave-assisted steady domain wall motion driven by adiabatic spin transfer torque can be adequately described by three domain wall collective coordinates. Analytical expression for the domain wall velocity showed that there are two contributions to the steady domain wall motion. One is derived from the nonlinear oscillation of domain wall width excited by the microwave field, and the other is from the heterodyne process between the width oscillation and the microwave field. The former always propels a domain wall to move in the positive direction, which is defined as the direction of the applied current. The latter contribution to the domain wall velocity can be positive or negative, depending on the polarization of the microwave field. The final domain wall velocity is determined by the competition between those two contributions, which indicates that by simply changing the polarization of the microwave field, the direction of the domain wall motion can be reversed. Our analysis demonstrated that the characteristics of domain wall motion can be tuned by selective excitation of nonlinear domain wall dynamics.
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Affiliation(s)
- D Wang
- School of Physics and Electronics, Central South University, Changsha, Hunan, People's Republic of China
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Sharma S, Muralidharan B, Tulapurkar A. Proposal for a Domain Wall Nano-Oscillator driven by Non-uniform Spin Currents. Sci Rep 2015; 5:14647. [PMID: 26420544 PMCID: PMC4588506 DOI: 10.1038/srep14647] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 09/02/2015] [Indexed: 11/25/2022] Open
Abstract
We propose a new mechanism and a related device concept for a robust, magnetic field tunable radio-frequency (rf) oscillator using the self oscillation of a magnetic domain wall subject to a uniform static magnetic field and a spatially non-uniform vertical dc spin current. The self oscillation of the domain wall is created as it translates periodically between two unstable positions, one being in the region where both the dc spin current and the magnetic field are present, and the other, being where only the magnetic field is present. The vertical dc spin current pushes it away from one unstable position while the magnetic field pushes it away from the other. We show that such oscillations are stable under noise and can exhibit a quality factor of over 1000. A domain wall under dynamic translation, not only being a source for rich physics, is also a promising candidate for advancements in nanoelectronics with the actively researched racetrack memory architecture, digital and analog switching paradigms as candidate examples. Devising a stable rf oscillator using a domain wall is hence another step towards the realization of an all domain wall logic scheme.
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Affiliation(s)
- Sanchar Sharma
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Bhaskaran Muralidharan
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Ashwin Tulapurkar
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Shevchenko A, Barabash M. A general formalism for the determination of the effective mass of the nanoscale structural inhomogeneities of the domain wall in uniaxial ferromagnets. NANOSCALE RESEARCH LETTERS 2015; 10:159. [PMID: 25983671 PMCID: PMC4424233 DOI: 10.1186/s11671-015-0861-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 03/14/2015] [Indexed: 06/04/2023]
Abstract
On the basis of the method of gyrotropic Thiele forces, we build a formalism that allows the determination of the effective mass of the nanoscales structural elements of the domain wall (DW): vertical Bloch line and Bloch point in uniaxial ferromagnets. As shown, the effective mass of these magnetic inhomogeneities depends on the value of the gyrotropic domain wall bend that is created by their movement.
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Affiliation(s)
- Andriy Shevchenko
- />G.V. Kurdymov Institute of Metal Physics, National Academy of Science of Ukraine, 36 Vernadskogo Pr., 03680 Kyiv−142, Ukraine
| | - Maksym Barabash
- />Technical Centre, National Academy of Science of Ukraine, 13 Pokrovskya Str., 04070 Kyiv, Ukraine
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Iwasaki J, Koshibae W, Nagaosa N. Colossal spin transfer torque effect on skyrmion along the edge. NANO LETTERS 2014; 14:4432-4437. [PMID: 24988528 DOI: 10.1021/nl501379k] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We study by the micromagnetic simulations the skyrmion motion along the edge driven by the current transverse to it. We found that (i) the velocity is enhanced by the factor of ∼ 1/α (α: the Gilbert damping) with the maximum value determined only by the confining force from the edge, (ii) the inertia appear due to the confining potential with the coordinate perpendicular to the edge playing the role of the kinetic momentum, and (iii) the collision between the two skyrmions is almost elastic without causing any internal distortions.
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Affiliation(s)
- Junichi Iwasaki
- Department of Applied Physics, The University of Tokyo , 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Shevchenko AB, Barabash MY. The Bloch point in uniaxial ferromagnets as a quantum mechanical object. NANOSCALE RESEARCH LETTERS 2014; 9:132. [PMID: 24646347 PMCID: PMC3994561 DOI: 10.1186/1556-276x-9-132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 02/28/2014] [Indexed: 06/03/2023]
Abstract
Quantum effects such as tunneling through pinning barrier of the Bloch Point and over-barrier reflection from the defect potential of one have been investigated in ferromagnets with uniaxial strong magnetic anisotropy. It is found that these phenomena can be appeared only in subhelium temperature range.
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Affiliation(s)
- Andriy Borisovich Shevchenko
- G.V. Kurdymov Institute of Metal Physics, National Academy of Science of Ukraine, 36 Vernadskogo pr., Kyiv 142, 03680, Ukraine
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Suzuki M, Kudo K, Kojima K, Yasue T, Akutsu N, Diño WA, Kasai H, Bauer E, Koshikawa T. Magnetic domain patterns on strong perpendicular magnetization of Co/Ni multilayers as spintronics materials: I. Dynamic observations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:406001. [PMID: 24025861 DOI: 10.1088/0953-8984/25/40/406001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Materials with perpendicular magnetic anisotropy can reduce the threshold current density of the current-induced domain wall motion. Co/Ni multilayers show strong perpendicular magnetic anisotropy and therefore it has become a highly potential candidate of current-induced domain wall motion memories. However, the details of the mechanism which stabilizes the strong perpendicular magnetization in Co/Ni multilayers have not yet been understood. In the present work, the evolution of the magnetic domain structure of multilayers consisting of pairs of 2 or 3 monolayers (ML) of Ni and 1 ML of Co on W(110) was investigated during growth with spin-polarized low-energy electron microscopy. An interesting phenomenon, that the magnetic domain structure changed drastically during growth, was revealed. In the early stages of the growth the magnetization alternated between in-plane upon Co deposition and out-of-plane upon Ni deposition. The change of the magnetization direction occurred within a range of less than 0.2 ML during Ni or Co deposition, with break-up of the existing domains followed by growth of new domains. The Ni and Co thickness at which the magnetization direction switched shifted gradually with the number of Co/Ni pairs. Above 3-4 Co/Ni pairs it stayed out-of-plane. The results indicate clearly that the Co-Ni interfaces play the important role of enhancing the perpendicular magnetic anisotropy.
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Affiliation(s)
- Masahiko Suzuki
- Fundamental Electronics Research Institute, Osaka Electro-Communication University, Neyagawa, Osaka 572-8530, Japan
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Shibata J, Tatara G, Kohno H. Effect of spin current on uniform ferromagnetism: domain nucleation. PHYSICAL REVIEW LETTERS 2005; 94:076601. [PMID: 15783838 DOI: 10.1103/physrevlett.94.076601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2004] [Revised: 11/11/2004] [Indexed: 05/24/2023]
Abstract
A large spin current applied to a uniform ferromagnet leads to a spin-wave instability as pointed out recently. In this Letter, it is shown that such spin-wave instability is absent in a state containing a domain wall, which indicates that nucleation of magnetic domains occurs above a certain critical spin current. This scenario is supported also by an explicit energy comparison of the two states under spin current.
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Affiliation(s)
- Junya Shibata
- Frontier Research System (FRS), The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Tatara G, Kohno H. Theory of current-driven domain wall motion: spin transfer versus momentum transfer. PHYSICAL REVIEW LETTERS 2004; 92:086601. [PMID: 14995801 DOI: 10.1103/physrevlett.92.086601] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Indexed: 05/24/2023]
Abstract
A self-contained theory of the domain wall dynamics in ferromagnets under finite electric current is presented. The current has two effects: one is momentum transfer, which is proportional to the charge current and wall resistivity (rho(w)); the other is spin transfer, proportional to spin current. For thick walls, as in metallic wires, the latter dominates and the threshold current for wall motion is determined by the hard-axis magnetic anisotropy, except for the case of very strong pinning. For thin walls, as in nanocontacts and magnetic semiconductors, the momentum-transfer effect dominates, and the threshold current is proportional to V(0)/rho(w), V0 being the pinning potential.
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Affiliation(s)
- Gen Tatara
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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