Diluted magnetic semiconductors with narrow band gaps; Theoretical study of Mn-doped BaZnAs and BaZnSb

Gu, B.; Maekawa, Sadamichi

The diluted magnetic semiconductors (DMS) have received considerable attention owing to potential applications based on the use of both their charge and spin degrees of freedom in electronic devices. For (Ga,Mn)As, a classic example of DMS, the highest Curie temperature has been Tc = 190 K. Owing to simultaneous doping of charge and spin induced by Mn substitution, it is difficult to individually optimize charge and spin densities in (Ga,Mn)As. To overcome these difficulties, here we propose a method to realize DMS with p- and n-type carriers by choosing host semiconductors with a narrow band gap. By employing a combination of the density function theory and quantum Monte Carlo simulation, we demonstrate such semiconductors using Mn-doped or Cr-doped BaZnAs, which has a band gap of 0.2 eV. In addition, we found a new non-toxic DMS Mn-doped BaZnSb, of which the Curie temperature Tc is predicted to be higher than that of Mn-doped BaZnAs, the Tc of which was up to 230 K in the recent experiment.