We calculated magnetic exchange constants and magnetocaloric properties of Ni2Mn1-xCuxGa Heusler alloys by ab initio and Monte Carlo methods. The ab initio study of the influence of the Cu excess x on the strength of magnetic interactions revealed that Cu weakens Mn-Ni interaction and has a complex impact on the Mn-Mn interactions. Theoretically calculated magnetic phase diagram of Ni2Mn1- xCuxGa is in a good agreement with available experimental data. Calculated by the Monte Carlo method the isothermal magnetic entropy change Δ S m a g in a Ni2Mn0.75Cu0.25Ga alloy is significantly smaller around the coupled magnetostructural phase transition temperature than the reported earlier experimental Δ S m a g. This discrepancy is ascribed to an overestimation of the experimental Δ S m a g at the magnetostructural phase transition. Theoretically determined adiabatic temperature change Δ T a d in Ni2Mn 0.75Cu0.25Ga agrees well with Δ T a d measured experimentally by a direct method.
ASJC Scopus subject areas
- Physics and Astronomy(all)