Histogram Monte Carlo study of multicritical behavior in the hexagonal easy-axis Heisenberg antiferromagnet

TL;DR

This paper uses histogram Monte Carlo simulations to investigate the critical behavior of a hexagonal easy-axis Heisenberg antiferromagnet, revealing complex multicritical phenomena and phase transition structures.

Contribution

It provides a detailed Monte Carlo analysis of multicritical points and phase boundaries in the model, highlighting deviations from standard scaling theory.

Findings

Multiphase point exhibits scaling-consistent structure.

No umbilicus observed at the bicritical point.

Complex multicritical behavior identified.

Abstract

The results of a detailed histogram Monte-Carlo study of critical-fluctuation effects on the magnetic-field temperature phase diagram associated with the hexagonal Heisenberg antiferromagnet with weak axial anisotropy are reported. The multiphase point where three lines of continuous transitions merge at the spin-flop boundary exhibits a structure consistent with scaling theory but without the usual umbilicus as found in the case of a bicritical point.