First-Principles and Monte Carlo Studies of Magnetocaloric Effects

Abstract

We have performed \textit{ab initio} electronic structure calculations and Monte Carlo simulations of magnetically frustrated intermetallic materials where complex magnetic configurations and chemical disorder lead to rich phase diagrams. With lowering of temperature, we find for magnetic Heusler alloys a ferromagnetic phase which transforms to an antiferromagnetic phase at the magnetostructural phase transition and to a cluster spin glass at still lower temperatures. We discuss chemical bonding features of Ni$_2$MnGa and the giant magnetocaloric effec of Ni-Mn-In with Co and Cr substitution as well as the origin of the magnetostructural transition.The numerical simulations allow a complete characterization of the magnetically frustrated materials.