Influence of magnetic-field-induced tuning of disorder and band structure on the magnetoresistance of paramagnetic dilute magnetic semiconductors

Abstract

We study theoretically the magnetotransport in p-type wide-gap dilute magnetic semiconductors in the paramagnetic phase. Two models (referred to as mobility model and network model) based on a minimal description of the valence-band structure and the acceptor state of the dilute magnetic semiconductors are discussed. In both models, band filling effects, magnetic-field splitting of the band states due to the $p-d$ exchange interaction, as well as effects of magnetic-field independent disorder are included whereas carrier-carrier interactions other than those responsible for the local magnetism of the Mn ions are neglected. Despite the exclusion of many-body effects in the bands, positive as well as negative magnetoresistance effects are predicted which show a qualitative agreement with recent experiments on p-type dilute magnetic semiconductors [Ye et al., J. Supercond. 16, 159 (2003); Nam et al., ibid. 16, 335 (2003)]. The differences between the two models arise from a different, model-specific weighting of disorder and occupation effects.