Fundamentals of half-metallic Full-Heusler alloys

TL;DR

This review discusses the electronic and magnetic properties of half-metallic full-Heusler alloys, highlighting their potential for spintronic applications, the relationship between valence electrons and magnetic moments, and effects of disorder and doping.

Contribution

It provides an overview of the fundamental properties of full-Heusler alloys, including analytical insights into disorder effects and mechanisms for achieving half-metallic ferrimagnetism.

Findings

Total spin magnetic moment scales linearly with valence electrons.

Disorder can destroy half-metallicity in these alloys.

Doping can induce fully-compensated half-metallic ferrimagnetism.

Abstract

Intermetallic Heusler alloys are amongst the most attractive half-metallic systems due to the high Curie temperatures and the structural similarity to the binary semiconductors. In this review we present an overview of the basic electronic and magnetic properties of the half-metallic full-Heusler alloys like Co$_2$MnGe. Ab-initio results suggest that the electronic and magnetic properties in these compounds are intrinsically related to the appearance of the minority-spin gap. The total spin magnetic moment in the unit cell, $M_t$, scales linearly with the number of the valence electrons, $Z_t$, such that $M_t=Z_t-24$ for the full-Heusler alloys opening the way to engineer new half-metallic alloys with the desired magnetic properties. Moreover we present analytical results on the disorder in Co$_2$Cr(Mn)Al(Si) alloys, which is susceptible to destroy the perfect half-metallicity of the bulk compounds and thus degrade the performance of devices. Finally we discuss the appearance of the half-metallic ferrimagnetism due to the creation of Cr(Mn) antisites in these compounds and the Co-doping in Mn$_2$VAl(Si) alloys which leads to the fully-compensated half-metallic ferrimagnetism.