Comparison of predicted ferromagnetic tendencies of Mn substituting the Ga site in III-V's and in I-III-VI2 chalcopyrite semiconductors

We report density-functional calculations of the ferromagnetic (FM) stabilization energy delta=E-FM-E-AFM for differently oriented Mn pairs in III-V's (GaN, GaP, GaAs) and chalcopyrite (CuGaS2, CuGaSe2, CuGaTe2) semiconductors. Ferromagnetism is found to be the universal ground state (delta<0) in all cases. The order of FM stability in III-V's is GaN>GaP>GaAs, whereas in chalcopyrites it is CuGaS2>CuGaSe2>CuGaTe2. Considering both groups, the order is GaN-->GaP-->GaAs-->CuGaS2-->CuGaSe2-->GaSbapproximate toCuGaTe(2). The stronger FM stabilization in III-V's is attributed to the stronger covalent coupling between the Mn 3d and the anion p orbitals. In contrast to expectations based on Ruderman-Kittel-(Kasuya)-Yosida, (i) all Mn-Mn pair separations show FM, with no FM to antiferromagnetic oscillations and, (ii) FM is orientationally dependent, with <110> Mn-Mn pairs being the most FM. (C) 2004 American Institute of Physics.