Ferromagnetism in Mn-doped GaN: From Clusters to Crystals

TL;DR

This study investigates the magnetic interactions of Mn-doped GaN, revealing ferromagnetic coupling and clustering tendencies, with implications for increasing Mn concentration in GaN through porous substrates.

Contribution

It provides first-principles analysis of Mn magnetic coupling in GaN clusters and crystals, highlighting ferromagnetic behavior and clustering effects.

Findings

Magnetic coupling is ferromagnetic with moments of 2.0 to 4.0 Bohr magnetons.

Mn atoms tend to cluster and bind more strongly to N atoms.

Potential to increase Mn concentration using porous substrates.

Abstract

The magnetic coupling between doped Mn atoms in clusters as well as crystals of GaN has been studied from first principles using molecular orbital theory for clusters and linearized muffin tin orbitals-tight binding formulation (LMTO-TB) for crystals. The calculations, based on density functional theory and generalized gradient approximation for exchange and correlation, reveal the coupling to be ferromagnetic with a magnetic moment ranging from 2.0 to 4.0 Bohr magnetons per Mn atom depending on its environment. Mn atoms also tend to cluster and bind more strongly to N atoms than to Ga atoms. The significant binding of Mn to GaN clusters further indicates that it may be possible to increase the Mn concentration in GaN by using a porous substrate that offers substantial interior surface sites.