Mechanism for ferromagnetism in diluted magnetic semiconductors

Kee Joo Chang

Korea Advanced Institute of Science and Technology

Diluted magnetic semiconductors have recently attracted much attention because of the potential use of both charge and spin of electrons for spintronic devices. In GaMnAs alloys, where the Curie temperature T_c is limited to 110 K, it is well established that free holes generated by Mn atoms are responsible for magnetic interactions between Mn ions. Using similar arguments, nitrides and oxides with wide band gaps were suggested that T_c could be as high as room temperature. However, experimental results so far are quite controversial, and no ferromagnetic state was observed in some samples. In this talk, I will present the reasults of first-pinciples pseudopotential calculations for the magnetic properties of GaMnN and ZnCoO alloys. I will discuss the mechanism for ferromagnetism and also the limitation of first-principles electronic structure calculations for diluted magnetic semiconductors.