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 $\text{CrMn}Z$ $\left(Z=\text{P},\text{As},\text{Sb}\right)$ semi-Heusler compounds.

• Received 4 December 2008

DOI:https://doi.org/10.1103/PhysRevB.79.100406