Robustness and stability of half-metallic ferromagnetism in alkaline-earth metal mononitrides against doping and deformation

TL;DR

This study uses ab-initio calculations to demonstrate that CaN and SrN mononitrides are robust half-metallic ferromagnets with high Curie temperatures, stable against doping and deformation, making them promising for magnetoelectronic applications.

Contribution

First comprehensive analysis of the magnetic stability of alkaline-earth mononitrides under doping and deformation using ab-initio methods.

Findings

CaN and SrN are half-metallic with 1.0 μB magnetic moment.

Curie temperatures are above room temperature (480 K and 415 K).

Magnetic properties are stable under doping and deformation.

Abstract

We employ ab-initio electronic structure calculations and study the magnetic properties of CaN and SrN compounds crystallizing in the rocksalt structure. These alkaline-earth metal mononitrides are found to be half-metallic with a total spin magnetic moment per formula unit of 1.0 $\mu_B$. The Curie temperature is estimated to be 480 K for CaN and 415 K for SrN well-above the room temperature. Upon small degrees of doping with holes or electrons, the rigid-band model suggests that the magnetic properties are little affected. Finally we studied for these alloys the effect of deformation taking into account tetragonalization keeping constant the unit cell volume which models the growth on various substrates. Even large degrees of deformation only marginally affect the electronic and magnetic properties of CaN and SrN in the rocksalt structure. Finally, we show that this stands also for the zincblende structure. Our results suggest that alkaline-earth metal mononitrides are promising materials for magnetoelectronic applications.