Possible impurity-induced ferromagnetism in (formula presented) chalcopyrite semiconductors

Recently reported room-temperature ferromagnetic (FM) semiconductors (formula presented) and (formula presented) point to a possible important role of (formula presented) chalcopyrite semiconductors in “spintronic” studies. Here, structural, electronic, and magnetic properties of (i) Mn-doped (formula presented) (formula presented) or Cd and (formula presented) or As) chalcopyrites and (ii) the role of S as impurity in (formula presented) are studied by first-principles density functional calculations. We find that the total energy of the antiferromagnetic (AFM) state is lower than the corresponding FM state for all systems with Mn composition (formula presented) 0.50, and 1.0. This prediction is in agreement with a recent experimental finding that (formula presented) experiences a FM to AFM transition for T less than 47 K. Furthermore, a possible transition to the half-metallic FM phase is predicted in (formula presented) due to the electrons introduced by n-type S doping, which indicates the importance of carriers for FM coupling in magnetic semiconductors. As expected, the total magnetic moment for the FM phase is reduced by one (formula presented) with each S substituting P.