Magnetoresistance of InMnAs magnetic semiconductors

We report on the magnetotransport properties of an InMnAs magnetic semiconductor thin film over the temperature range of 19–61 K. A small negative magnetoresistance is observed that becomes positive with increasing field. We find that the magnetoresistance of these films is well described by a semi-empirical model that takes into account the third order p–d exchange Hamiltonian describing the negative contribution and a two-band model for the positive contribution. The negative magnetoresistance of the film originates from spin-dependent scattering of carriers by localized magnetic moments while the positive magnetoresistance is attributed to conduction via spin-split hybridized p–d sub-bands with different conductivities and mobilities.