Thermodynamic and critical properties of an antiferromagnetically stacked triangular Ising antiferromagnet in a field

TL;DR

This study investigates the phase transitions and critical behavior of a stacked triangular Ising antiferromagnet in a magnetic field using Monte Carlo simulations, revealing a second-order transition and highly degenerate low-temperature phases.

Contribution

It provides new insights into the phase diagram and critical properties of a 3D stacked triangular Ising antiferromagnet under an external field, highlighting non-conventional crossover phenomena.

Findings

One second-order phase transition from paramagnetic to partially disordered phase.

Identification of highly degenerate low-temperature phases with long-range order in specific directions.

Crossover behaviors characterized by linear-chain-like excitations rather than traditional phase transitions.

Abstract

We study a stacked triangular lattice Ising model with both intra- and inter-plane antiferromagnetic interactions in a field, by Monte Carlo simulation. We find only one phase transition from a paramagnetic to a partially disordered phase, which is of second order and 3D XY universality class. At low temperatures we identify two highly degenerate phases: at smaller (larger) fields the system shows long-range ordering in the stacking direction (within planes) but not in the planes (stacking direction). Nevertheless, crossovers to these phases do not have a character of conventional phase transitions but rather linear-chain-like excitations.