Temperature-dependent criticality in random 2D Ising models

TL;DR

This study investigates how temperature influences critical behavior in 2D random Ising models, revealing temperature-dependent critical exponents in Barkhausen noise consistent with experimental findings.

Contribution

It provides the first detailed analysis of temperature effects on critical exponents in 2D disordered Ising models through Monte Carlo simulations.

Findings

Critical temperature varies with disorder strength.

Critical exponents of Barkhausen noise depend on temperature.

Results align with experimental observations.

Abstract

We consider 2D random Ising ferromagnetic models, where quenched disorder is represented either by random local magnetic fields (Random Field Ising Model) or by a random distribution of interaction couplings (Random Bond Ising Model). In both cases we first perform zero- and finite-temperature Monte-Carlo simulations to determine how the critical temperature depends on the disorder parameter. We then focus on the reversal transition triggered by an external field, and study the associated Barkhausen noise. Our main result is that the critical exponents characterizing the power-law associated with the Barkhausen noise exhibit a temperature dependence in line with existing experimental observations.