First-principles calculation of the intersublattice exchange interactions and Curie temperatures of the full Heusler alloys ${\mathrm{Ni}}_{2}\mathrm{Mn}X$ $(X=\mathrm{Ga},\mathrm{In},\mathrm{Sn},\mathrm{Sb})$

First-principles calculation of the intersublattice exchange interactions and Curie temperatures of the full Heusler alloys ${Ni}_{2} Mn X$ $(X = Ga, In, Sn, Sb)$

E. Şaşıoğlu, L. M. Sandratskii, and P. Bruno

Phys. Rev. B 70, 024427 – Published 30 July 2004

Abstract

The interatomic exchange interactions and Curie temperatures in $Ni$ -based full Heusler alloys ${Ni}_{2} Mn X$ with $X = Ga, In, Sn$ , and $Sb$ are studied within the framework of the density-functional theory. The calculation of the exchange parameters is based on the frozen-magnon approach. Despite closeness of the experimental Curie temperatures for all four systems, their magnetism appeared to differ strongly. This difference involves both the $Mn − Mn$ and $Mn − Ni$ exchange interactions. The Curie temperatures, $T_{C}$ , are calculated within the mean-field approximation by solving a matrix equation for a multisublattice system. Good agreement with experiment for all four systems is obtained. The role of different exchange interactions in the formation of $T_{C}$ of the systems is discussed.