Spin and thermal conductivity in a classical disordered spin chain

Abstract

Transport quantities of the classical spin chain with the quenched disorder in the antiferromagnetic coupling Ji are evaluated using the dynamical simulation at finite temperatures T > 0 . Since the classical model is nonintegrable, spin and thermal conductivities remain finite even in the pure case. On the other hand, the role of disorder becomes crucial at low T leading to a vanishing transport due to the Anderson localization within the linearized regime. The crossover from the insulator to the conductor appears both for the spin and thermal transport at quite low T * J. Still the many-body localization regime at T > 0 evidenced by extremely short mean free paths can be strongly enhanced by introducing into the model an additional staggered field.

Spin dynamics simulations of topological magnon insulators: From transverse current correlation functions to the family of magnon Hall effects

“…We note in passing that the thermal conductivities shown here are similar to those in Ref. [40] for a chain with disorder. An exception is that we find κ → const.…”

“…J th (t)J th (0) dt for B = 0 of a chain of ferromagnetically coupled spins (Refs. [39,40]; lattice constant a). We simulated a chain of N = 500 spins coupled by J = 1 meV.…”

Density correlations and transport in models of many‐body localization

“…Dynamical thermal conductivity and its d.c. value have been much less investigated within the framework of models relevant for MBL . Related question of localization and vanishing of d.c. spin and energy transport has been addressed within classical disordered Heiseberg chain , where there is no signature of vanishing d.c. transport. That is, in spite of Anderson‐like localization for as a common property, there seems to be no classical analogue of the MBL physics.…”

Energy repartition in the nonequilibrium steady state

“…In the following, we limit ourselves to the temperature distribution of nonequilibrium ferromagnetic magnons. Off-diagonal terms T kk (k = k ) encode the magnonic spin current, which can be obtained from the spin continuity equation [28,29] …”