Hysteresis in the T=0 RFIM: beyond metastable dynamics

TL;DR

This paper investigates how allowing the RFIM to be trapped in non-metastable states affects hysteresis and avalanche behavior at zero temperature, revealing that critical exponents remain unchanged despite increased dissipation.

Contribution

It introduces a modified dynamics for the RFIM that captures non-metastable trapping, providing new insights into hysteresis and critical behavior at T=0.

Findings

Hysteresis dissipation increases with non-metastable trapping.

Critical exponents are robust to the modified dynamics.

Avalanche distributions follow finite-size scaling consistent with known phase transition behavior.

Abstract

We present a numerical study of the zero-temperature response of the Gaussian random-field Ising model (RFIM) to a slowly varying external field, allowing the system to be trapped in microscopic configurations that are not fully metastable. This modification of the standard single-spin-flip dynamics results in an increase of dissipation (hysteresis) somewhat similar to that observed with a finite driving rate. We then study the distribution of avalanches along the hysteresis loop and perform a finite-size scaling analysis that shows good evidence that the critical exponents associated to the disorder-induced phase transition are not modified.