Control of defect binding and magnetic interaction energies in dilute magnetic semiconductors by charge state manipulation

Dilute magnetic semiconductors exhibit a unique entanglement of magnetism and semiconductor properties. Their properties are dominated by short-range chemical and magnetic interactions among the magnetic impurities diluted therein. The microscopic structure and defect distribution are of crucial importance; and indeed, it has been shown that clustering, phase separation, and complex formation of the magnetic impurities, possibly involving other intrinsic or extrinsic defects, can dramatically alter the magnetic properties of a given sample. Detailed knowledge of the underlying short-range chemical and magnetic interactions, in turn, can be used to "design" new materials with target magnetic properties. This paper describes the Fermi-level dependence of these short-range chemical and magnetic interactions, i.e., how these interactions depend on defect charge states.