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We calculate the low-temperature thermodynamic quantities (magnetization, correlation functions, transverse and longitudinal correlation lengths, spin susceptibility, and specific heat) of the frustrated one-dimensional spin-half J1-J2…

Strongly Correlated Electrons · Physics 2015-05-27 M. Härtel , J. Richter , D. Ihle

A macroscopic equation of motion for the magnetization of a ferromagnet at elevated temperatures should contain both transverse and longitudinal relaxation terms and interpolate between Landau-Lifshitz equation at low temperatures and the…

Statistical Mechanics · Physics 2009-10-31 D. A. Garanin

We describe a minimal model, based on a spin only Hamiltonian with a single energy scale for itinerant electron metamagnetism. Within this model the metamagnetic critical field is directly proportional to the temperature where a peak in the…

Strongly Correlated Electrons · Physics 2018-08-20 P. Kumar , B. S. Shivaram , V. Celli

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 consider the general Landau-Lifshitz-Gilbert (LLG) dynamical theory underlying the magnetization switching rates of a thin film uniaxial magnet subject to spin-torque effects and thermal fluctuations (thermal noise). After discussing the…

Mesoscale and Nanoscale Physics · Physics 2013-08-01 D. Pinna , A. D. Kent , D. L. Stein

By molecular dynamics simulation, we have investigated classical Heisenberg spins, which are arrayed on a finite simple cubic lattice and interact with each other only by the dipole-dipole interaction, and have found its peculiar it…

Statistical Mechanics · Physics 2007-05-23 Katsuyoshi Matsushita , Ryoko Sugano , Akiyoshi Kuroda , Yusuke Tomita , Hajime Takayama

We study magnetic fluctuations in a system of interacting spins on a lattice at high temperatures and in the presence of a spatially varying magnetic field. Starting from a microscopic Hamiltonian we derive effective equations of motion for…

Statistical Mechanics · Physics 2013-03-28 Andrew Sykes , Dmitry Solenov , Dmitry Mozyrsky

We develop a new method to probe the local spin dynamic autocorrelation function, using magnetic field dependent muon depolarization measurements. We apply this method to muSR experiments in the dilute Heisenberg spin glass AgMn(p at. %) at…

Strongly Correlated Electrons · Physics 2009-11-07 Amit Keren , Galina Bazalitsky , Ian Campbell , James S. Lord

We present the results of muon-spin relaxation measurements of spin excitations in the one-dimensional quantum Heisenberg antiferromagnet Cu(pyz)(NO$_{3}$)$_{2}$. Using density-functional theory we propose muon sites and assess the degree…

Strongly Correlated Electrons · Physics 2015-05-20 F. Xiao , J. S. Möller , T. Lancaster , R. C. Williams , F. L. Pratt , S. J. Blundell , D. Ceresoli , A. M. Barton , J. L. Manson

In conventional micromagnetism magnetic domain configurations are calculated based on a continuum theory for the magnetization which is assumed to be of constant length in time and space. Dynamics is usually described with the…

Materials Science · Physics 2008-05-05 O. Chubykalo-Fesenko , U. Nowak , R. W. Chantrell , D. Garanin

Using exact diagonalization, Monte-Carlo, and mean-field techniques, characteristic temperature scales for ferromagnetic order are discussed for the Ising and the classical anisotropic Heisenberg model on finite lattices in one and two…

Mesoscale and Nanoscale Physics · Physics 2011-04-12 E. Y. Vedmedenko , N. Mikuszeit , T. Stapelfeldt , R. Wieser , M. Potthoff , A. Lichtenstein , R. Wiesendanger

Numerical integration of a stochastic Landau-Lifshitz-Gilbert equation is used to study dynamic processes in single-domain nanoscale magnets at nonzero temperatures. Special attention is given to including thermal fluctuations as a Langevin…

Materials Science · Physics 2009-10-31 Gregory Brown , M. A. Novotny , Per Arne Rikvold

The magnetization dynamics of ferromagnets are often formulated in terms of the Landau-Lifshitz-Gilbert (LLG) equation. The reactive part of this equation describes the response of the magnetization in terms of effective fields, whereas the…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 Arne Brataas , Yaroslav Tserkovnyak , Gerrit E. W. Bauer

We present a spin-rotation-invariant Green-function theory for the dynamic spin susceptibility in the spin-1/2 antiferromagnetic Heisenberg model on a stacked honeycomb lattice. Employing a generalized mean-field approximation for arbitrary…

Strongly Correlated Electrons · Physics 2017-03-27 A. A. Vladimirov , D. Ihle , N. M. Plakida

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

Recently, an anomalous temperature evolution of spin wave excitations has been observed in a van der Waals metallic ferromagnet Fe$_3$GeTe$_2$ (FGT) [S. Bao, et al., Phys. Rev. X 12, 011022 (2022)], whose theoretical understanding yet…

Strongly Correlated Electrons · Physics 2024-01-02 Yuan Gao , Junsen Wang , Qiaoyi Li , Qing-Bo Yan , Tao Shi , Wei Li

We use Monte Carlo and molecular dynamics simulation to study a magnetic tip-sample interaction. Our interest is to understand the mechanism of heat dissipation when the forces involved in the system are magnetic in essence. We consider a…

Computational Physics · Physics 2015-06-26 R. A. Dias , M. Rapini , P. Z. Coura , B. V. Costa

Recent experiments [Jo et al., Science 325, 1521 (2009)] have presented evidence of ferromagnetic correlations in a two-component ultracold Fermi gas with strong repulsive interactions. Motivated by these experiments we consider spin drag,…

Quantum Gases · Physics 2010-06-04 R. A. Duine , Marco Polini , H. T. C. Stoof , G. Vignale

We investigate the temperature dependence of the coefficients in the Landau-Lifshitz-Gilbert equation in ferromagnetic GaMnAs by employing the Zener model. We first calculate the hole spin relaxation time based on the microscopic kinetic…

Materials Science · Physics 2012-02-10 K. Shen , M. W. Wu

We study the correlation functions of quantum spin $1/2$ ladders at finite temperature, under a magnetic field, in the gapless phase at various relevant temperatures $T\neq 0$, momentum $q$ and frequencies $\omega$. We compute those…

Strongly Correlated Electrons · Physics 2019-05-15 N. Kestin , T. Giamarchi