First-principles prediction of a new class of ferromagnetic semiconductors

Ferromagnetism in I-III-VI2 chalcopyrite semiconductors is predicted to arise from holes provided by Mn doping in the illustrative case of CuGaSe2. The first-principles calculations within the generalized gradient approximation to density functional theory demonstrate that Mn substitutes for Ga sites in CuGaSe2 with a formation energy that is similar to0.25 eV lower than that for Cu sites. Ferromagnetic CuGa1-xMnxSe2 is found to be a half-metallic material with a magnetic moment of 4 mu(B) per Mn for xgreater than or equal to0.25, and its estimated Curie temperature is more than 110 K. We suggest that higher Curie temperatures may be achieved for this new class of ferromagnetic semiconductors based on Mn-doped I-III-VI2 chalcopyrites by employing other materials with a smaller lattice constant such as CuGaSe2 and CuAlSe2. (C) 2002 Elsevier Science B.V. All rights reserved.