Nonequilibrium multicritical behavior in anisotropic Heisenberg ferromagnet driven by oscillating magnetic field

TL;DR

This study uses Monte Carlo simulations to explore the nonequilibrium multicritical behavior of an anisotropic Heisenberg ferromagnet under a rotating elliptically polarized magnetic field, revealing multiple dynamic phase transitions and their phase diagram.

Contribution

It provides the first detailed analysis of multicritical behavior in anisotropic Heisenberg ferromagnets driven by oscillating magnetic fields, including phase diagrams and transition nature.

Findings

Multiple dynamical phase transitions observed at low anisotropy.

Phase diagram mapped in field amplitude and temperature.

Diverging length scale near transition points indicated by variance analysis.

Abstract

The Heisenberg ferromagnet (uniaxially anisotropic along z-direction), in the presence of time dependent (but uniform over space) magnetic field, is studied by Monte Carlo simulation. The time dependent magnetic field was taken as elliptically polarised in such a way that the resulting field vector rotates in the XZ plane. In the limit of low anisotropy, the dynamical responses of the system are studied as functions of temperature and the amplitudes of the magnetic field. As the temperature decreases, it aws found that the system undergoes multiple dynamical phase transitions. In this limit, the multiple transitions were studied in details and the phase diagram for this observed multicritical behaviour was drawn in the field amplitude and temperature palne.The natures (continuous/discontinuous) of the transitions are determined by the temperature variations of fourth order Binder cumulant ratio and the distributions of the order parameter near the transition points. The transitions are supported by finite size study. The temperature variations of the variances of dynamic order parameter components (for different system sizes) indicate the existence of diverging length scale near the dynamic transition points. The frequency dependences of the transition temperatures of the multiple dynamic transition are also studied briefly.