Influence of the lattice geometry on the thermodynamical properties of two-dimensional spin systems

TL;DR

This paper uses Monte Carlo simulations to study how lattice geometry affects the thermodynamical properties of two-dimensional mixed spin Heisenberg networks, aiming to interpret experimental molecule-based magnets.

Contribution

It introduces a classical approximation model for quantum spins in 2D Heisenberg networks considering lattice geometry effects, validated through thermodynamical property calculations.

Findings

Lattice geometry significantly influences specific heat and magnetic susceptibility.

The classical model effectively captures quantum effects in the studied systems.

Results align with experimental observations of molecule-based magnets.

Abstract

Various types of mixed spin two-dimensional Heisenberg networks are investigated by means of Monte Carlo simulations. This study aims at interpreting quantitatively the thermodynamical properties of two-dimensional molecule-based magnets recently synthesized. The proposed model requires that: (i) one of the two magnetic centers has a spin large enough to be treated as a classical spin; (ii) the zero field Hamiltonian is isotropic; (iii) the quantum spins have only classical spins as neighbours. The quantum Hamiltonian is then replaced by a classical one with effective ferromagnetic interactions. The temperature dependence of both the specific heat and magnetic susceptibility are calculated. The effect of the lattice geometry is analysed.