Stability and magnetic properties of Mn-substituted ScN from first principles

TL;DR

This study uses first-principles DFT calculations to explore the structural and magnetic properties of Mn-substituted ScN, revealing a stable ferromagnetic phase with significant magnetic moments at Mn sites and insights into electronic structure modifications due to Mn doping.

Contribution

The paper provides the first detailed theoretical analysis of Mn substitution effects on the stability and magnetic properties of ScN using DFT and all-electron methods.

Findings

ScN is a narrow-gap semiconductor with a 0.54 eV indirect band gap.

Mn substitution stabilizes a ferromagnetic phase with high magnetic moments at Mn atoms.

The ternary Sc$_{0.75}$Mn$_{0.25}$N prefers a face centered tetragonal-rocksalt structure.

Abstract

We present a spin density functional theory (DFT) study for semiconducting ScN and Mn-substituted ScN. Their structural and magnetic properties have been investigated using the all electrons augmented spherical wave method (ASW) with a generalized gradient GGA functional for treating the effects of exchange and correlation. Band structure calculations show that ScN is semiconductor with a narrow indirect band gap $\Gamma$-X of 0.54 eV. The total-energy versus volume calculations show that ternary Sc$_{0.75}$Mn$_{0.25}$N nitride is more stable in face centered tetragonal-rocksalt (fct-rocksalt) structure, found experimentally, than the cubic rocksalt one. Spin polarized results, at theoretical equilibrium, indicate that the ground state of Sc$_{0.75}$Mn$_{0.25}$N is ferromagnetic with a high moment at Mn-atom (3.44$\mu_B$), and zero moment on Sc and N ones. The magnetovolume effects of Mn-substitution in ScN lattice are discussed. The electronic structures analyzed from site/spin projected density of states and chemical bonding, for both the mononitride and the ternary alloy, are reported. A discussion of the structural and magnetic properties of Sc$_{0.75}$Mn$_{0.25}$N is given with a comparison to ScN, in order to get insights of the Mn-substitution effects.