Transport Properties of (Ga,Mn)As Diluted Magnetic Semiconductors in the Bulk and in Layered Systems

Transport properties of systems based on diluted magnetic semiconductors (Ga,Mn)As are investigated theoretically by means of the Kubo linear response theory. The underlying electronic structure is obtained within the local spin-density approximation using the scalarrelativistic tight-binding linear muffin-tin orbital (TB-LMTO) method. The effect of substitutional randomness on the electronic structure and on the transport properties is systematically described in the coherent potential approximation (CPA). The quantities studied include the residual resistivities of the bulk alloys as well as conductances of epitaxial trilayers Cr/(Ga,Mn)As/Cr (001) in the current-perpendicular-to-plane (CPP) orientation. The results witness that various compensating defects such as As antisite atoms and Mn interstitials have much stronger detrimental effect on the spin polarization of the CPP conductances as compared to their influence on the spin polarization of the bulk conductivities.