Axial and off-axial dynamic transitions in uniaxially anisotropic Heisenberg ferromagnet: A comparison

TL;DR

This study investigates the dynamic phase transitions in a uniaxially anisotropic Heisenberg ferromagnet under sinusoidal magnetic fields, revealing how anisotropy influences the nature of axial and off-axial transitions through Monte Carlo simulations.

Contribution

It provides a comparative analysis of axial and off-axial dynamic transitions in anisotropic Heisenberg ferromagnets and relates these to Ising model transitions at high anisotropy.

Findings

Axial transition is discontinuous at low anisotropy and continuous at high anisotropy.

Off-axial transition remains continuous across all anisotropy levels.

In the infinite anisotropy limit, axial and off-axial transitions differ from Ising model transitions.

Abstract

Uniaxially anisotropic Heisenberg ferromagnet, in the presence of a magnetic fieldvarying sinusoidally in time, is studied by Monte Carlo Simulation. The axial (field applied only along the direction of anisotropy) and off-axial (field applied only along the direction which is prependicular to the direction of anisotropy) dynamic transitions are studied. By studying the distribution of the dynamic order parameter component, it is observed that the axial transition is discontinuous for low anisotropy and becomes continuous in high anisotropy. The off-axial transition is found to be continuous for all values of anisotropy. In the infinite anisotropy limit, both types of transitions are compared with athat observed in an Ising ferromagnet for the same value of the field and frequency. The infinitely anisotropic axial transition and dynamic transition in the Ising ferromagnet occur at different temperatures, whereas the infinitely anisotropic off-axial transition and the equilibrium ferro-para transition in the Ising model occur at the same temperature.