Monte Carlo simulations of ${\rm Rb_2MnF_4}$, a classical Heisenberg antiferromagnet in two-dimensions with dipolar interaction

TL;DR

This study uses Monte Carlo simulations to explore the phase diagram of the quasi-two-dimensional magnetic compound Rb2MnF4, revealing distinct Ising and XY phases influenced by dipolar interactions and analyzing the phase boundary with finite size scaling.

Contribution

We perform detailed Monte Carlo simulations of a classical Heisenberg model including dipolar interactions to map the phase diagram of Rb2MnF4, highlighting the nature of phase boundaries and critical points.

Findings

Identification of Ising-like antiferromagnetic phase at low fields

Discovery of XY phase at high magnetic fields

Analysis indicating a bicritical point at zero temperature

Abstract

We study the phase diagram of a quasi-two dimensional magnetic system ${\rm Rb_2MnF_4}$ with Monte Carlo simulations of a classical Heisenberg spin Hamiltonian which includes the dipolar interactions between ${\rm Mn}^{2+}$ spins. Our simulations reveal an Ising-like antiferromagnetic phase at low magnetic fields and an XY phase at high magnetic fields. The boundary between Ising and XY phases is analyzed with a recently proposed finite size scaling technique and found to be consistent with a bicritical point at T=0. We discuss the computational techniques used to handle the weak dipolar interaction and the difference between our phase diagram and the experimental results.