Stability of ferromagnetism in the half-metallic pnictides and similar compounds: A first-principles study

TL;DR

This study uses first-principles calculations to analyze exchange interactions and Curie temperatures in transition-metal alloys, identifying promising compounds like MnSi and CrAs for spintronics due to their high stability and Curie temperatures.

Contribution

It provides a detailed first-principles analysis of ferromagnetism stability and Curie temperatures in zinc-blende transition-metal alloys, highlighting promising candidates for spintronics.

Findings

CrAs, MnSi, MnGe have Curie temperatures around 1000 K.

CrSe and MnAs tend to antiferromagnetism under lattice compression.

MnC exhibits a majority-spin half-metallic gap.

Abstract

Based on first-principles electron structure calculations and employing the frozen-magnon approximation we study the exchange interactions in a series of transition-metal binary alloys crystallizing in the zinc-blende structure and calculate the Curie temperature within both the mean-field approximation (MFA) and random-phase approximation (RPA). We study two Cr compounds, CrAs and CrSe, and four Mn compounds: MnSi, MnGe, MnAs and MnC. MnC, MnSi and MnGe are isovalent to CrAs and MnAs is isoelectronic with CrSe. Ferromagnetism is particular stable for CrAs, MnSi and MnGe: All three compounds show Curie temperatures around 1000 K. On the other hand, CrSe and MnAs show a tendency to antiferromagnetism when compressing the lattice. In MnC the half-metallic gap is located in the majority-spin channel contrary to the other five compounds. The large half-metallic gaps, very high Curie temperatures, the stability of the ferromagnetism with respect to the variation of the lattice parameter and a coherent growth on semiconductors make MnSi and CrAs most promising candidates for the use in spintronics devises.