Thermodynamics of a mixed quantum-classical Heisenberg model in two dimensions

TL;DR

This paper investigates a mixed quantum-classical Heisenberg model on a decorated hexagonal lattice, analyzing its thermodynamic properties and relevance to a synthesized molecular magnet using high-temperature expansions and Monte Carlo simulations.

Contribution

It introduces a fully classical effective model derived from a quantum-classical Heisenberg system and demonstrates its accuracy in describing experimental magnetic susceptibility.

Findings

The classical model accurately predicts magnetic susceptibility in the paramagnetic phase.

High-temperature expansions and Monte Carlo simulations effectively analyze the model's thermal properties.

The model captures key features of the molecular magnetic compound's behavior.

Abstract

We study the planar antiferromagnetic Heisenberg model on a decorated hexagonal lattice, involving both classical spins (occupying the vertices) and quantum spins (occupying the middle of the links). This study is motivated by the description of a recently synthesized molecular magnetic compound. First, we trace out the spin 1/2 degrees of freedom to obtain a fully classical model with an effective ferromagnetic interaction. Then, using high temperature expansions and Monte Carlo simulations, we analyse its thermal and magnetic properties. We show that it provides a good quantitative description of the magnetic susceptibility of the molecular magnet in its paramagnetic phase.