Field-induced XY behavior in the S=1/2 antiferromagnet on the square lattice

TL;DR

This study uses quantum Monte Carlo simulations to explore how a magnetic field induces XY behavior and a BKT transition in a 2D S=1/2 antiferromagnetic Heisenberg model, revealing a rich phase diagram and thermodynamic properties.

Contribution

It demonstrates the field-induced XY behavior and BKT transition in the square lattice antiferromagnet using advanced quantum Monte Carlo methods.

Findings

Field induces a BKT transition at finite temperature.

Extended temperature range of XY behavior observed.

Phase diagram of the system constructed.

Abstract

Making use of the quantum Monte Carlo method based on the worm algorithm, we study the thermodynamic behavior of the S=1/2 isotropic Heisenberg antiferromagnet on the square lattice in a uniform magnetic field varying from very small values up to the saturation value. The field is found to induce a Berezinskii-Kosterlitz-Thouless transition at a finite temperature, above which a genuine XY behavior in an extended temperature range is observed. The phase diagram of the system is drawn, and the thermodynamic behavior of the specific heat and of the uniform and staggered magnetization is discussed in sight of an experimental investigation of the field-induced XY behavior.