Nonzero macroscopic magnetization in half-metallic antiferromagnets at finite temperatures

TL;DR

This study demonstrates that half-metallic antiferromagnets exhibit nonzero macroscopic magnetization at finite temperatures due to sublattice inequivalence, leading to a ferrimagnetic state, as shown through advanced computational methods.

Contribution

It reveals the finite-temperature behavior of half-metallic antiferromagnets using combined density-functional and Green's function techniques, highlighting a novel temperature-induced ferrimagnetic state.

Findings

Macroscopic magnetization persists at finite temperatures.

Inequivalent sublattices cause different exchange interactions.

Finite-temperature ferrimagnetic state observed in CrMnZ compounds.

Abstract

Combining density-functional theory calculations with many-body Green's-function technique, we reveal that the macroscopic magnetization in half-metallic antiferromagnets does not vanish at finite temperature as for the T=0 limit. This anomalous behavior stems from the inequivalent magnetic sublattices which lead to different intrasublattice exchange interactions. As a consequence, the spin fluctuations suppress the magnetic order of the sublattices in a different way leading to a ferrimagnetic state at finite temperatures. Computational results are presented for the half-metallic antiferromagnetic CrMnZ (Z=P,As,Sb) semi-Heusler compounds.