Magnetic phase transition in coupled spin-lattice systems: A replica-exchange Wang-Landau study

TL;DR

This study investigates the magnetic phase transition in coupled spin-lattice systems using a novel parallel Monte Carlo method, revealing slight effects of lattice vibrations on transition temperature and sensitivity to interatomic potentials.

Contribution

It introduces a replica-exchange Wang-Landau Monte Carlo approach for simulating coupled spin-lattice models, providing new insights into their finite-temperature magnetic properties.

Findings

Transition temperature is marginally affected by lattice vibrations.

Peak amplitude in specific heat curve is slightly influenced by lattice vibrations.

Results depend on the choice of interatomic potential.

Abstract

Coupled, dynamical spin-lattice models provide a unique test ground for simulations investigating the finite-temperature magnetic properties of materials under the direct influence of the lattice vibrations. These models are constructed by combining a coordinate-dependent interatomic potential with a Heisenberg-like spin Hamiltonian, facilitating the treatment of both the atomic coordinates and spins as explicit phase variables. Using a model parameterized for bcc iron, we study the magnetic phase transition in these complex systems via the recently introduced, massively parallel replica-exchange Wang-Landau Monte Carlo method. Comparison with the results obtained from rigid lattice (spin only) simulations show that the transition temperature as well as the amplitude of the peak in the specific heat curve is marginally affected by the lattice vibrations. Moreover, the results were found to be sensitive to the particular choice of the interatomic potential.