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We investigate theoretically the dynamics of magnetization coupled to the surface Dirac fermions of a three dimensional topological insulator, by deriving the Landau-Lifshitz-Gilbert (LLG) equation in the presence of charge current. Both…

Mesoscale and Nanoscale Physics · Physics 2014-11-20 Takehito Yokoyama , Jiadong Zang , Naoto Nagaosa

The phenomenological Landau-Lifshitz-Gilbert (LLG) equation of motion remains as the cornerstone of contemporary magnetisation dynamics studies, wherein the Gilbert damping parameter has been attributed to first-order relativistic effects.…

Other Condensed Matter · Physics 2018-06-28 Ritwik Mondal , Marco Berritta , Peter M. Oppeneer

The gyromagnetic relation - i.e. the proportionality between the angular momentum $\vec L$ (defined by an inertial tensor) and the magnetization $\vec M$ - is evidence of the intimate connections between the magnetic properties and the…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 J. -E. Wegrowe , M. -C. Ciornei

Starting from the Dirac-Kohn-Sham equation we derive the relativistic equation of motion of spin angular momentum in a magnetic solid under an external electromagnetic field. This equation of motion can be written in the form of the…

Materials Science · Physics 2016-10-20 Ritwik Mondal , Marco Berritta , Peter M. Oppeneer

The damping of magnetization, represented by the rate at which it relaxes to equilibrium, is successfully modeled as a phenomenological extension in the Landau-Lifschitz-Gilbert equation. This is the damping torque term known as Gilbert…

Other Condensed Matter · Physics 2009-04-01 M. C. Hickey , J. S. Moodera

The Landau-Lifshitz-Gilbert (LLG) equation is a fascinating nonlinear evolution equation both from mathematical and physical points of view. It is related to the dynamics of several important physical systems such as ferromagnets, vortex…

Pattern Formation and Solitons · Physics 2011-01-06 M. Lakshmanan

The influence of possible magnetic inertia effects has recently drawn attention in ultrafast magnetization dynamics and switching. Here we derive rigorously a description of inertia in the Landau-Lifshitz-Gilbert equation on the basis of…

Other Condensed Matter · Physics 2017-07-26 Ritwik Mondal , Marco Berritta , Ashis K. Nandy , Peter M. Oppeneer

We investigate the possibility of exciting self-oscillation in a perpendicular ferromagnet by the spin Hall effect on the basis of a nonlinear analysis of the Landau-Lifshitz-Gilbert (LLG) equation. In the self-oscillation state, the energy…

Mesoscale and Nanoscale Physics · Physics 2015-03-13 Tomohiro Taniguchi

Spin precession in magnetic materials is commonly modelled with the classical phenomenological Landau-Lifshitz-Gilbert (LLG) equation. Based on a quantized spin+environment Hamiltonian, we here derive a general spin operator equation of…

Quantum Physics · Physics 2022-11-02 J. Anders , C. R. J. Sait , S. A. R. Horsley

In the framework of the Landau-Lifshitz equations without any dissipation (an approximation which may also be helpful for finite but weak Gilbert damping), with all interactions included, for general ground states, geometries and domain…

Materials Science · Physics 2016-08-31 U. Krey

A theoretical model based on the Landau-Lifshitz-Bloch equation is developed to study the spin-torque effect in ferrimagnets. Experimental findings, such as the temperature dependence, the peak in spin torque, and the angular-momentum…

Materials Science · Physics 2018-11-21 Zhifeng Zhu , Xuanyao Fong , Gengchiau Liang

We discuss the theoretical basis for the search of the possible experimental manifestations of the torsion field at low energies. First, the quantum field theory in an external gravitational field with torsion is reviewed. The…

High Energy Physics - Theory · Physics 2007-05-23 Ilya L. Shapiro

Spin torques play a crucial role in operative properties of modern spintronic devices. To study current-driven magnetization dynamics, spin-torque terms providing the action of spin-polarized currents have previously often been added in a…

Materials Science · Physics 2018-12-26 Ritwik Mondal , Marco Berritta , Peter M. Oppeneer

We analyze the Landau-Lifshitz-Gilbert equation when the precession motion of the magnetic moments is additionally subjected to an uniaxial anisotropy and is driven by a multiplicative coupled stochastic field with a finite correlation time…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 Thomas Bose , Steffen Trimper

The traditional Landau-Lifshitz-Gilbert (LLG) equation has often delineated the linear and nonlinear magnetization dynamics, even at ultrashort timescales e.g., femtoseconds. In contrast, several other non-relativistic and relativistic spin…

The dynamics of a magnetic moment or spin are of high interest to applications in technology. Dissipation in these systems is therefore of importance for improvement of efficiency of devices, such as the ones proposed in spintronics. A…

Mesoscale and Nanoscale Physics · Physics 2023-08-29 Robin C. Verstraten , Tim Ludwig , Rembert A. Duine , Cristiane Morais Smith

The pseudo-PT symmetric Dirac equation is proposed and analyzed by using a non-unitary Foldy-Wouthuysen transformations. A new spin operator PT symmetric expectation value (called the mean spin operator) for an electron interacting with a…

Quantum Physics · Physics 2022-10-26 Y. Bouguerra , S. Mehani , K. Bechane , M. Maamache , P. -A. Hervieux

Using an effective Hamiltonian including the Zeeman and internal interactions, we describe the quantum theory of magnetization dynamics when the spin system evolves non-adiabatically and out of equilibrium. The Lewis-Riesenfeld dynamical…

Other Condensed Matter · Physics 2008-11-26 F. M. Saradzhev , F. C. Khanna , Sang Pyo Kim , M. de Montigny

In the present paper we consider a theory of gravity in which not only curvature but also torsion is explicitly present in the Lagrangian, both with their own coupling constant. In particular, we discuss the couplings to Dirac fields and…

General Relativity and Quantum Cosmology · Physics 2012-12-06 Luca Fabbri , Stefano Vignolo , Cosimo Stornaiolo

Domain patterns are simulated by the Landau-Lifshitz-Gilbert (LLG) equation with an easy-axis anisotropy. If the Gilbert damping is removed from the LLG equation, it merely describes the precession of magnetization with a ferromagnetic…

Statistical Mechanics · Physics 2016-12-23 Kazue Kudo
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