Abstract:
Diluted magnetic semiconductors, such as (Ga,Mn)As, are important materials combining ferromagnetic behavior with a sensitivity to doping characteristic for semiconductors (possible applications e.g. in spin-electronics). It was assumed that in the well defined samples Mn simply substitutes for the host cation. However, the presence of interstitial Mn may explain some peculiar properties of (Ga,Mn)As such as the low doping efficiency of Mn acceptors. We used the first principle calculations to obtain total energies of supercells simulating various geometric and magnetic configurations of Mn atoms in (Ga,Mn)As. We investigated the formation energies of different defects in this system as well as the compositional dependence of the lattice constant of (Ga,Mn)As containing various native defects. We found that the strong tendency to compensation is the intrinsic property of the Mn subsystem. The Mn interstitials are attracted to the substitutional Mn and form stable and magnetically inactive pairs. We found that the efficient pairing is not restricted to Mnint in the T(Ga3Mn) position.