Ferromagnetism in Mn-doped GaN: From clusters to crystals

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 µ B 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.

First-principles study on the magnetic properties of transition-metal atoms doped (ZnS)12 cluster

“…Studies of these systems are driven not only by academic interest in understanding the origin of ferromagnetism but also by the potential applications [2]. In an effort to raise the Curie temperature to values above room temperature, whence DMS could become commercially visible, there has been a push towards hosts with larger band gaps, such as zinc sulfide (ZnS, 3.7 eV at 300 K) [3,4].…”

Jahn-Teller distortion and ferromagnetism in the dilute magnetic semiconductors GaAs:Mn and cubic GaN:Mn

“…However, the reported Curie temperatures 1 are too low to have significant practical impact. Recently, there has been interest in wide bandgap semiconductors, such as GaN 26 , which may exhibit higher Curie temperatures 29,30,31,32,33,34,35 . Since there has been tremendous progress on the growth of high-quality (Ga, Mn)N epitaxial layers 36,37 , GaN:Mn is a promising high Tc ferromagnetic semiconductor.…”

Cr-Doped III–V Nitrides: Potential Candidates for Spintronics

“…[12][13][14][15] Successful growth of III-nitrides (AlN, GaN, and InN) with the zincblende structure on GaAs substrates by molecular-beam epitaxial technique has been reported. 16,17 Half-metallicity is theoretically predicted in Ga 1Àx Mn x N with 6.5% and 12.5% Mn concentration [18][19][20] and also in Al 0.97 Mn 0.03 N. 14 It has been experimentally observed that the Curie temperature of AlCrN (2% Cr) is higher than that of AlMnN (2% Mn). 9 Wu and Liu predicted a 600 K Curie temperature for AlCrN with 0.05 £ x £ 0.15 and found experimentally that Cr is magnetically active at 3% doping in GaN or at 7% in AlN.…”