Abstract
The transport properties of diluted magnetic semiconductors (DMS) are calculated using the dynamical mean field theory (DMFT) and the Boltzmann transport theory. Within the DMFT we study the density of states and the dc resistivity, which are strongly parameter dependent such as temperature, doping, density of the carriers, and the strength of the carrier-local impurity spin exchange coupling. Characteristic qualitative features are found distinguishing weak, intermediate, and strong carrier-spin coupling and allowing quantitative determination of important parameters defining the underlying ferromagnetic mechanism. We find that spin-disorder scattering, formation of bound state, and the population of the minority spin band are all operational in the DMFT in different parameter ranges. We also develop a complementary Boltzmann transport theory for scattering by screened ionized impurities. The difference in the screening properties between paramagnetic and ferromagnetic states gives rise to the temperature dependence (increase or decrease) of resistivity, depending on the carrier density, as the system goes from the paramagnetic phase to the ferromagnetic phase. The metallic behavior below for optimally doped DMS samples can be explained in the Boltzmann theory by temperature dependent screening and the thermal change of carrier spin polarization.
8 More- Received 3 March 2005
DOI:https://doi.org/10.1103/PhysRevB.72.035210
©2005 American Physical Society