Theoretical prediction of maximum Curie temperatures of Fe-based dilute magnetic semiconductors by first-principles calculations

Recently, Fe-based dilute magnetic semiconductors (DMSs), such as (In,Fe)As, (In,Fe)Sb and (Ga,Fe)Sb, have strongly attracted scientific and industrial attention, because of their high Curie temperatures and n-type carrier induced ferromagnetism. Several experiments showed that the ferromagnetic properties in Fe-based DMSs are strongly related to the inhomogeneous distribution of the Fe atoms, i.e., the Curie temperatures are modulated by the spinodal nano-decomposition, depending on crystal growth conditions. In this work, we predict the maximum Curie temperatures of the Fe-based DMSs with the spinodal nano-decomposition, on the basis of the Korringa-Kohn-Rostoker (KKR) Green’s function method within the density functional theory. The magnetic exchange coupling constants between the Fe atoms are calculated by the Liechtenstein’s formula, and then the Curie temperatures are estimated by the mean field approximation. It is found, from our calculations, that one can expect very high Curie temperatures beyond the room temperature in Fe-based DMSs, if the many Fe atoms gather together in the host semiconductor with keeping the zinc-blende structure and additional n- or p-type carriers are introduced.