Standing spin wave mode in RFIM at T=0: Patterns and nonequilibrium phases

TL;DR

This study investigates the dynamical phases of the 2D random field Ising model at zero temperature under standing magnetic field waves, revealing pinned, structured, and random phases through Monte Carlo simulations.

Contribution

It introduces a detailed analysis of phase boundaries and the emergence of standing spin wave modes in RFIM with different quenched field distributions at T=0.

Findings

Identified three distinct dynamical phases: pinned, structured, and random.

Derived analytical phase boundaries for uniform and bimodal quenched fields.

Demonstrated the disappearance of regular spin wave patterns at high random field values.

Abstract

The dynamical responses of random field Ising model at zero temperature, driven by standing magnetic field wave, is studied by Monte Carlo simulation in two dimensions. The three different kinds of distribution of quenched random field are used here, uniform, bimodal and Gaussian. In all cases, three distinct dynamical phases were observed, namely, the pinned, structured and random. In the pinned phase no spin flip is observed. In the structured phase standing spin wave modes are observed. The random phase is shown no regular pattern. For a fixed value of the amplitude of the standing magnetic field wave, in the region of small quenched field, the system remains in a pinned phase. In the intermediate range of values of random field, a standing spin wave mode (structured phase) is observed. The regular pattern of this spin wave mode disappears for higher values of random field yielding a random phase. The comprehensive phase baundaries are drawn in all three cases. The boundary of pinned phase are analytically calculated for uniform and bimodal types of quenched random fields.