Relation of Curie temperature and conductivity: (Ga,Mn)As alloy as a case study

Experimental investigations of diluted magnetic semiconductors indicate a strong relation between Curie temperature and conductivity. Both quantities depend non trivially on the concentration of magnetic impurities, the carrier density, and the presence of compensating defects. We calculate both Curie temperature and conductivity of (Ga,Mn)As alloys in a selfconsistent manner based on the same first principles Hamiltonian in which the presence of compensating defects is taken into account. The effect of As-antisites and Mn-interstitials is determined separately and a good agreement between theory and experiment exists only in the case where the dominating mechanism of is due to the Mn-interstitials.Comment: The manuscript is accepted for publication in AP

On the origin of temperature dependence of interlayer exchange coupling in metallic trilayers

We study the influence of collective magnetic excitations on the interlayer exchange coupling (IEC) in metallic multilayers. The results are compared to other models that explain the temperature dependence of the IEC by mechanisms within the spacer or at the interfaces of the multilayers. As a main result we find that the reduction of the IEC with temperature shows practically the same functional dendence in all models. On the other hand the influence of the spacer thickness, the magnetic material, and an external field are quite different. Based on these considerations we propose experiments, that are able to determine the dominating mechanism that reduces the IEC at finite temperatures.Comment: 8 pages, 7 figures, accepted for PR

Correlated Doping in Semiconductors: The Role of Donors in III-V Diluted Magnetic Semiconductors

We investigate the compositional dependence of the total energy of the mixed crystals (Ga,Mn)As co-doped with As, Sn, and Zn. Using the ab initio LMTO-CPA method we find a correlation between the incorporation of acceptors (Mn, Zn) and donors (Sn, antisite As). In particular, the formation energy of As_Ga is reduced by approx. 0.1 eV in the presence of Mn, and vice versa. This leads to the self-compensating behavior of (Ga,Mn)As.Comment: 8 pages, 2 figures, presented at the XXXI Int. School of Semiconducting Compounds, Jaszowiec 2002, Polan