Introduction to half-metallic Heusler alloys: Electronic Structure and Magnetic Properties

TL;DR

This review discusses the electronic and magnetic properties of half-metallic Heusler alloys, highlighting their potential for spintronic applications due to their high Curie temperatures and tunable magnetic moments.

Contribution

It provides an overview of the electronic structure and magnetic behavior of half- and full-Heusler alloys, emphasizing the relationship between their properties and the minority-spin gap.

Findings

Electronic and magnetic properties are linked to the minority-spin gap.

Total spin magnetic moment scales linearly with valence electrons.

Guidelines for engineering new half-metallic alloys are proposed.

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 both Heusler families: the so-called half-Heusler alloys like NiMnSb and the the full-Heusler alloys like Co$_2$MnGe. \textit{Ab-initio} results suggest that both the electronic and magnetic properties in these compounds are intrinsically related to the appearance of the minority-spin gap. The total spin magnetic moment $M_t$ scales linearly with the number of the valence electrons $Z_t$, such that $M_t=Z_t-24$ for the full-Heusler and $M_t=Z_t-18$ for the half-Heusler alloys, thus opening the way to engineer new half-metallic alloys with the desired magnetic properties.