Dilute magnetic III–V semiconductor spintronics materials: A first-principles approach

Group-III nitride semiconductors, such as GaN, when doped with 3d transition metals such as Mn or Cr show ferromagnetism with high Curie temperature. Such dilute magnetic semiconductors (DMS) with larger band gaps and smaller lattice constants compared to GaAs based DMS, are potential candidates for room temperature spintronics devices. We have investigated the magnetic coupling between doped Mn (or Cr) atoms in clusters as well as crystals of GaN from first principles using molecular orbital theory for (GaN)xTM2 clusters and TB-LMTO band calculations for wurtzite structured (Ga14TM2)N16 supercells. Our calculations reveal that the coupling between TM-impurity atoms is ferromagnetic with a bulk magnetic moment of ∼3.5 μB per Mn atom and ∼2.7 μB per Cr atom.