Spin Dynamics in the Presence of Spin-orbit Interactions

Spin Dynamics in the Presence of Spin-orbit Interactions
Author: Xin Liu
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN:

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We study the spin dynamics in a high-mobility two dimensional electron gas (2DEG) system with generic spin-orbit interactions (SOIs). We derive a set of spin dynamic equations which capture the purely exponential to the damped oscillatory spin evolution modes observed in different regimes of SOI strength. Hence we provide a full treatment of the D'yakonov-Perel's mechanism by using the microscopic linear response theory from the weak to the strong SOI limit. We show that the damped oscillatory modes appear when the electron scattering time is larger than half of the spin precession time due to the SOI, in agreement with recent observations. We propose a new way to measure the scattering time and the relative strength of Rashba and linear Dresselhaus SOIs based on these modes and optical grating experiments. We discuss the physical interpretation of each of these modes in the context of Rabi oscillation. In the finite temperature, We study the spin dynamics in the presence of impurity and electron-electron (e-e) scattering in a III-V semiconductor quantum well. Starting from the Keldysh formalism, we develop the spin-charge dynamic equation at finite temperature in the presence of inelastic scattering which provide a new approach to describe the spin relaxation from the weak to the strong spin-orbit coupling (SOC) regime. In the weak SOC regime, our theory shows that when the system is near the SU(2) symmetry point, because the spin relaxation due to DP mechanism is suppressed dramatically, the spin relaxation is dominated by the Elliott-Yafet (EY) mechanism in a wide temperature regime. The non-monotonic temperature dependence of enhanced-lifetime of spin helix mode is due to the competition between the DP and EY mechanisms. In the strong SOC regime, the our theory is consistent to the previous theoretical results at zero temperature.

Itinerant Spin Dynamics in Structures of Reduced Dimensionality

Itinerant Spin Dynamics in Structures of Reduced Dimensionality
Author: Paul Thomas Wenk
Publisher:
Total Pages: 161
Release: 2011
Genre:
ISBN:

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In the present thesis results of the study of spin dynamics and quantum transport in disordered semiconductor quantum wires with spin-orbit coupling are presented. Starting from basic spin dynamics we derive the dependence of the weak localization correction to the conductance on the strength and the kind of spin-orbit interaction (linear and cubic Dresselhaus, as well as Rashba coupling), the width of the quantum wires as well as the mobility, temperature and Zeeman term. Furthermore, we exploit the connection found between the microscopic picture given by the Cooperon and the spin diffusion equation to extract the spin relaxation rate which shows the same wire dependencies as the weak localization correction. We also show how the result depends on the smoothness and the direction of the transverse confinement of the quantum wires. In this context we have addressed the question concerning long persisting or even persistent spin states in spintronic devices, presenting the corresponding optimal adjustment of spin orbit couplings of different kind and optimal alignment of the wire direction in semiconductor crystals. Experiments\cite{Holleitner2006,Holleitner2007,Kunihashi2009a,Lehnen2007,hu05_4,Schapers2009} which report the dimensional reduction of the spin relaxation rate in agreement with previous results were raising new questions, in particular as regarding the crossover from diffusive to ballistic wires, which we answer using modified Cooperon equation. In addition, we focus on the intrinsic spin Hall effect, which is only due to spin-orbit coupling. Having shown the basic features with analytical calculations, we solve the spin Hall conductivity in presence of binary and block-distributed impurities (Anderson model). At this we apply the Kernel Polynomial Method, which allows for a finite size analysis of the metal-insulator transition and the calculation of spin Hall conductivity in large systems compared with those addressable with exact diagonalization.

Spin-orbit Coupling Effects in Two-Dimensional Electron and Hole Systems

Spin-orbit Coupling Effects in Two-Dimensional Electron and Hole Systems
Author: Roland Winkler
Publisher: Springer Science & Business Media
Total Pages: 244
Release: 2003-10-10
Genre: Technology & Engineering
ISBN: 9783540011873

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The first part provides a general introduction to the electronic structure of quasi-two-dimensional systems with a particular focus on group-theoretical methods. The main part of the monograph is devoted to spin-orbit coupling phenomena at zero and nonzero magnetic fields. Throughout the book, the main focus is on a thorough discussion of the physical ideas and a detailed interpretation of the results. Accurate numerical calculations are complemented by simple and transparent analytical models that capture the important physics.

Random Walk Approach to Spin Dynamics in a Two-dimensional Electron Gas with Spin-orbit Coupling

Random Walk Approach to Spin Dynamics in a Two-dimensional Electron Gas with Spin-orbit Coupling
Author:
Publisher:
Total Pages:
Release: 2010
Genre:
ISBN:

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We introduce and solve a semiclassical random walk (RW) model that describes the dynamics of spin polarization waves in zinc-blende semiconductor quantum wells. We derive the dispersion relations for these waves, including the Rashba, linear and cubic Dresselhaus spin-orbit interactions, as well as the effects of an electric field applied parallel to the spin polarization wave vector. In agreement with calculations based on quantum kinetic theory [P. Kleinert and V.V. Bryksin, Phys. Rev. B 76, 205326 (2007)], the RW approach predicts that spin waves acquire a phase velocity in the presence of the field that crosses zero at a nonzero wave vector, q0. In addition, we show that the spin-wave decay rate is independent of field at q0 but increases as (q-q0)2 for q `"q0. These predictions can be tested experimentally by suitable transient spin grating experiments.

Symmetry, Spin Dynamics and the Properties of Nanostructures - Lecture Notes of the 11th International School on Theoretical Physics

Symmetry, Spin Dynamics and the Properties of Nanostructures - Lecture Notes of the 11th International School on Theoretical Physics
Author: Vitalii K. E. T. Al DUGAEV
Publisher: World Scientific
Total Pages: 326
Release: 2015-11-09
Genre: Science
ISBN: 9814740373

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"This book is a collection of lecture notes which were presented by invited speakers at the Eleventh School on Theoretical Physics "Symmetry and Structural Properties of Condensed Matter SSPCM 2014" in Rzeszów (Poland) in September 2014. The main challenge for the lecturers was the objective to present their subject as a review as well as in the form of introduction for beginners. Topics considered in the volume concentrate on: spin dynamics and spin transport in magnetic and non-magnetic structures, spin-orbit interaction in two-dimensional systems and graphene, and new mathematical method used in the condensed matter physics."--

Synthetic Spin-orbit Coupling In Cold Atoms

Synthetic Spin-orbit Coupling In Cold Atoms
Author: Wei Zhang
Publisher: World Scientific
Total Pages: 307
Release: 2018-07-25
Genre: Science
ISBN: 9813272546

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This is a review volume covering a wide range of topics in this newly developed research field. The intended audience corresponds to graduate students, post-docs and colleagues working in the field of cold atomic gases. This is the first review volume dedicated to this active research frontier, and provides a comprehensive and pedagogical summary of recent progresses in the field.

Atomistic Spin Dynamics

Atomistic Spin Dynamics
Author: Olle Eriksson
Publisher: Oxford University Press
Total Pages: 265
Release: 2017
Genre: Science
ISBN: 0198788665

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Several large experimental facilities that focus on detection and probing magnetization dynamics have been realized in Europe, USA and Japan. This book covers theoretical and practical aspects of the vibrant and emerging research field of magnetization dynamics.

Spin Dynamics and Damping in Ferromagnetic Thin Films and Nanostructures

Spin Dynamics and Damping in Ferromagnetic Thin Films and Nanostructures
Author: Anjan Barman
Publisher: Springer
Total Pages: 166
Release: 2017-12-27
Genre: Technology & Engineering
ISBN: 3319662961

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This book provides a comprehensive overview of the latest developments in the field of spin dynamics and magnetic damping. It discusses the various ways to tune damping, specifically, dynamic and static control in a ferromagnetic layer/heavy metal layer. In addition, it addresses all optical detection techniques for the investigation of modulation of damping, for example, the time-resolved magneto-optical Kerr effect technique.

Study of Domain Wall Dynamics in the Presence of Large Spin Orbit Coupling

Study of Domain Wall Dynamics in the Presence of Large Spin Orbit Coupling
Author: Safeer Chenattukuzhiyil
Publisher:
Total Pages: 0
Release: 2015
Genre:
ISBN:

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Magnetic domain wall (DW) dynamics is currently attracting tremendous interest both from a fundamental point of view as well as in relation with emerging magnetic memory and logic devices. New DW-based devices were recently proposed, for example to replace hard drive disks with higher density and faster date transfer. Moreover, in Magnetic Random Access Memory (MRAM), identified as one of the most promising candidate for DRAM and SRAM replacement, switching occurs through DW propagation. Control of current induced DW dynamics has long been a challenge mainly due to material imperfections. Only some years ago, fast and controllable motions were reported in multilayers presenting structural inversion asymmetry (SIA). More recently, a mechanism was proposed based on the presence of spin orbit torques and Dzyaloshinskii-Moriya interaction (DMI), both phenomena originating from the spin orbit interaction and needing (SIA).My initial objective was to test this model in two systems presenting different SIA. In Pt/Co/Pt multilayers with weak SIA, I studied both current and field induced DW motion and evidenced a chiral damping. This new phenomena, counterpart of the DMI for the dissipative aspects, influences both current and field induced dynamics and has to be taken into account for a complete picture of the mechanism. In Pt/Co/AlOx multilayers with strong SIA, I studied new geometries where the DW motion the and current flow are not collinear. I evidenced asymmetric DW motion as a function of this non-collinearity that cannot be explained with a simple SOT+DMI model. Based on these experimental results I introduce a new device concept named “magnetic origami”: the shape of the device governs the switching mechanism. This concept provides large flexibility to construct fast, low power non-volatile magnetic memory: different functionalities can be achieved on a wafer by simply mastering the shape of the different elements. I show the proof of concept of two such devices.

Ultrafast Magnetization Dynamics in the Presence of Strong Spin-Orbit Coupling

Ultrafast Magnetization Dynamics in the Presence of Strong Spin-Orbit Coupling
Author: Colleen Kantner
Publisher:
Total Pages: 162
Release: 2010
Genre:
ISBN:

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The time-resolved magneto-optical Kerr effect is used to study magnetization dynamics in thin films of SrRuO3. This thesis focuses on two topics in particular: the influence of epitaxial strain on magnetization dynamics and magnetic orientation, and the origin of the dramatic slowing down of the demagnetization time near the Curie temperature. Magnetization dynamics in SrRuO3 are initiated by a temperature dependent rotation of the magnetocrystalline anisotropy field direction upon thermal excitation by the laser. The resulting dynamics depend on the orientation of the anisotropy field in the sample. We observe a change in the orientation as a function of epitaxially strain by looking at SrRuO3grown on various substrates with (001) orientation and distinct in-plane lattice parameters. We find that in SrRuO3 films under compressive strain, the anisotropy field moves in a plane perpendicular to the film surface. Beyond a certain degree of tensile strain, the anisotropy field moves in the plane parallel to the surface of the film. Support of this result from theoretical calculations and XRD measurements is discussed and attempts to strain tune films with a piezoelectric substrate are described. Near the Curie temperature, the demagnetization time in SrRuO3/SrTiO3(111) is found to increase by more than a factor of ten. Here, we study this effect in detail and derive an equation for the demagnetization time in terms of the spin flip time, starting from detailed balance and borrowing from a recent spin-based model for demagnetization[57, 58]. The demagnetization time is found to be proportional to the spin flip time and inversely proportional to the reduced temperature near Tc, allowing us to measure the spin flip time. We also relate the spin flip time and the damping parameter to the Curie temperature and find that the previously speculated upon relationship between the damping parameter in SrRuO3 and the anomalous Hall effect is strengthened.