Landau-Lifschitz magnets: exact thermodynamics and transport

Fuente: arXiv
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Autores principales: Bastianello, Alvise, Krajnik, Žiga, Ilievski, Enej
Formato: Preprint
Publicado: 2024
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author Bastianello, Alvise
Krajnik, Žiga
Ilievski, Enej
author_facet Bastianello, Alvise
Krajnik, Žiga
Ilievski, Enej
contents The classical Landau--Lifshitz equation -- the simplest model of a ferromagnet -- provides an archetypal example for studying transport phenomena. In one-spatial dimension, integrability enables the classification of the spectrum of linear and nonlinear modes. An exact characterization of finite-temperature thermodynamics and transport has nonetheless remained elusive. We present an exact description of thermodynamic equilibrium states in terms of interacting modes. This is achieved by retrieving the classical Landau--Lifschitz model through the semiclassical limit of the integrable quantum spin-$S$ anisotropic Heisenberg chain at the level of the thermodynamic Bethe ansatz description. In the axial regime, the mode spectrum comprises solitons with unconventional statistics, whereas in the planar regime we additionally find two special types of modes of radiative and solitonic type. The obtained framework paves the way for analytical study of unconventional transport properties: as an example we study the finite-temperature spin Drude weight, finding excellent agreement with Monte Carlo simulations.
format Preprint
id arxiv_https___arxiv_org_abs_2404_12106
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Landau-Lifschitz magnets: exact thermodynamics and transport
Bastianello, Alvise
Krajnik, Žiga
Ilievski, Enej
Statistical Mechanics
Exactly Solvable and Integrable Systems
The classical Landau--Lifshitz equation -- the simplest model of a ferromagnet -- provides an archetypal example for studying transport phenomena. In one-spatial dimension, integrability enables the classification of the spectrum of linear and nonlinear modes. An exact characterization of finite-temperature thermodynamics and transport has nonetheless remained elusive. We present an exact description of thermodynamic equilibrium states in terms of interacting modes. This is achieved by retrieving the classical Landau--Lifschitz model through the semiclassical limit of the integrable quantum spin-$S$ anisotropic Heisenberg chain at the level of the thermodynamic Bethe ansatz description. In the axial regime, the mode spectrum comprises solitons with unconventional statistics, whereas in the planar regime we additionally find two special types of modes of radiative and solitonic type. The obtained framework paves the way for analytical study of unconventional transport properties: as an example we study the finite-temperature spin Drude weight, finding excellent agreement with Monte Carlo simulations.
title Landau-Lifschitz magnets: exact thermodynamics and transport
topic Statistical Mechanics
Exactly Solvable and Integrable Systems
url https://arxiv.org/abs/2404.12106