GIANT MAGNETOCALORIC EFFECT OF COMPRESSIBLE ISING AND HEISENBERG LATTICES

摘要

Since the discovery of giant magnetocaloric materials, it has become clear that magnetovolume coupling canrnlead to a large increase to a material's magnetocaloric effect, and so, to high-performance magneticrnrefrigerants. A simple and computationally inexpensive approach to gauge magnetovolume effects is via thernBean-Rodbell model, where a Curie temperature dependence on volume is included in the Weiss mean-fieldrnmodel. The thermodynamic properties of giant magnetocaloric materials are described, namely discontinuousrnmagnetization curves and large entropy change values. Moving to a microscopic model is a natural step tornbetter characterize giant magnetocaloric materials. In this work we show how an Ising/Heisenberg-typerninteraction together with elastic/magnetovolume coupling can be solved by a Monte-Carlo method,rnreproducing the thermodynamic properties of giant magnetocaloric systems. The low computational cost ofrnthis approach and the possibilities of simulating systems using Density Functional Theory calculatedrnmagnetic interaction parameters allow the computational study and design of (giant) magnetocaloricrnmaterials.