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First-principles study of exchange interactions and Curie temperatures of half-metallic ferrimagnetic full Heusler alloys Mn2VZ (Z=Al, Ge)

E. Sasioglu·L. M. Sandratskii·P. Bruno
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Abstract

We report the parameter-free, density functional theory calculations of interatomic exchange interactions and Curie temperatures of half-metallic ferrimagnetic full Heusler alloys Mn2VZ (Z=Al, Ge). To calculate the interatomic exchange interactions we employ the frozen-magnon approach. The Curie temperatures are calculated within the mean-field approximation to the classical Heisenberg Hamiltonian by solving a matrix equation for a multi-sublattice system. Our calculations show that, although a large magnetic moment is carried by Mn atoms, competing ferromagnetic (inter sublattice) and antiferromagnetic (intra sublattice) Mn-Mn interactions in Mn2VAl almost cancel each other in the mean-field experienced by the Mn atoms. In Mn2VGe the leading Mn-Mn exchange interaction is antiferromagnetic. In both compounds the ferromagnetism of the Mn subsystem is favored by strong antiferromagnetic Mn-V interactions. The obtained value of the Curie temperature of Mn2VAl is in good agrement with experiment. For Mn2VGe there is no experimental information available and our calculation is a prediction.

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E. Sasioglu, L. M. Sandratskii, P. Bruno. 2005-04-26. First-principles study of exchange interactions and Curie temperatures of half-metallic ferrimagnetic full Heusler alloys Mn2VZ (Z=Al, Ge). https://arxiv.org/abs/cond-mat/0504679

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