Spin-glass dynamics in the presence of a magnetic field: exploration of microscopic properties

TL;DR

This study combines experiments, theory, and simulations to analyze microscopic spin-glass dynamics under magnetic fields, focusing on correlation lengths, non-linear susceptibility, and the de Almeida-Thouless line near the transition temperature.

Contribution

It provides a comprehensive microscopic analysis of spin-glass dynamics in magnetic fields, integrating experimental data with large-scale simulations and reinterpreting previous results.

Findings

Correlation length $\xi(t,t_w;T)$ is consistent across experiments and simulations.

Reanalysis resolves previous disagreements about Zeeman energy.

Scaling relationships for magnetization growth are verified in simulations.

Abstract

The synergy between experiment, theory, and simulations enables a microscopic analysis of spin-glass dynamics in a magnetic field in the vicinity of and below the spin-glass transition temperature $T_\mathrm{g}$. The spin-glass correlation length, $\xi(t,t_\mathrm{w};T)$, is analysed both in experiments and in simulations in terms of the waiting time $t_\mathrm{w}$ after the spin glass has been cooled down to a stabilised measuring temperature $T<T_\mathrm{g}$ and of the time $t$ after the magnetic field is changed. This correlation length is extracted experimentally for a CuMn 6 at. % single crystal, as well as for simulations on the Janus II special-purpose supercomputer, the latter with time and length scales comparable to experiment. The non-linear magnetic susceptibility is reported from experiment and simulations, using $\xi(t,t_\mathrm{w};T)$ as the scaling variable. Previous experiments are reanalysed, and disagreements about the nature of the Zeeman energy are resolved. The growth of the spin-glass magnetisation in zero-field magnetisation experiments, $M_\mathrm{ZFC}(t,t_\mathrm{w};T)$, is measured from simulations, verifying the scaling relationships in the dynamical or non-equilibrium regime. Our preliminary search for the de Almeida-Thouless line in $D=3$ is discussed.