A linearized spin-wave theory for thermodynamics of quantum Heisenberg antiferromagnet on a square lattice

TL;DR

This paper develops a linearized spin-wave theory to analyze the thermodynamics of the quantum Heisenberg antiferromagnet on a square lattice, accurately capturing temperature-dependent properties across a wide range.

Contribution

It introduces a well-defined linearized spin-wave approach applicable at any finite temperature, reproducing known results and aligning with numerical simulations.

Findings

Quantitative agreement with Quantum Monte Carlo at low temperatures

Reproduction of high-temperature series expansion results

Consistent description of free energy, internal energy, entropy, and specific heat

Abstract

The thermodynamics of the quantum Heisenberg antiferromagnet on a square lattice is revisited through a linearized spin-wave theory which is well defined at any finite temperature. We re-examine in details the temperature dependence of the free energy, the internal energy, the entropy and the specific heat. Most conclusions of the thermodynamics in previous studies can be reproduced in our linearized spin-wave theory. Specially, our calculation at low temperature $T<J$ agrees quantitatively with the numerical Quantum Monte Carlo simulation and high temperature series expansions.