Mn-doped CuGaS2 chalcopyrites:: An ab initio study of ferromagnetic semiconductors -: art. no. 205206

Stimulated by our recent findings suggesting that the I-III-VI2 chalcopyrites could be a different class of ferromagnetic semiconductors, we performed first-principles calculations within density-functional theory and the generalized gradient approximation for Mn-doped CuGaS2. Our calculations confirm the previous theoretical predictions on CuGaSe2, that the ferromagnetic spin configuration is strongly favored. Mn is found to be, as expected, both a source of localized magnetic moments and an acceptor; thus, our results seem to support the general idea that ferromagnetism is stabilized through a carrier-mediated interaction. For all the systems, we find a half-metallic character, consistent with the integer value of the total magnetic moment of 4mu(B) per Mn atom. This is particularly important for spin-injection applications: in a significant energy range (i.e., about 0.5 eV in the dilute case) around the Fermi level relevant for spin injection, the holes will have a well-defined spin. A simple Heisenberg model to estimate the Curie temperature T-c in ordered CuMnxGa1-xS2 alloys gives T(c)similar to160 K, therefore suggesting the possible importance of this class of ferromagnetic semiconductors for spintronic applications.