First-principles calculation of stable magnetic state and Curie temperature in transition metal doped III-V semiconductors

Abstract

Stable magnetic state in the transition metal (TM) doped zincblende (ZB) type compounds (Al1−xMx)Sb and (Ga1−xMx)As are investigated on the basis of density functional theory, where M is the 3d TM atom namely Ti, V, Cr, Mn, Fe, Co, Ni and x is the fractional concentration of M. The electronic states and magnetic properties are calculated using the first-principles self-consistent Korringa-Kohn-Rostoker (KKR) Green's function method combined with the coherent potential approximation (CPA). Some of the calculated properties of ZB type materials (Al1−xMx)Sb and (Ga1−xMx)As exhibit stable ferromagnetic (FM) states relative to a corresponding disorder local moment (DLM) states. The total energy difference between FM and DLM states per unit cell is used to estimate their Curie temperature (TC) within the mean-field approximation. The calculated TC in Mn, and Cr doped cases are found to be above the room temperature (RT), whereas in Ti, and V doped cases TC remain below the RT. In addition, TC increases with doping concentrations in a range of dilute limit (x ≈ 20%) of magnetic atoms. On the other hand, Fe, and Co doped materials exhibit FM instability due to the dominating super-exchange interaction over the FM one.