Large positive magnetoresistance effects in the dilute magnetic semiconductor (Zn,Mn)Se in the regime of electron hopping.

Magnetoresistance in dilute magnetic semiconductors is studied in the hopping transport regime. Measurements performed on Cl-doped Zn_1-xMn_xSe with x<8% are compared with simulation results obtained by a hopping transport model. The energy levels of the Cl donors are affected by the magnetization of Mn atoms in their vicinity via the s-d exchange interaction. Compositional disorder, in particular, the random distribution of magnetic atoms, leads to a magnetic-field induced broadening of the donor energy distribution. As the energy distribution broadens, the electron transport is hindered and a large positive contribution to the magnetoresistance arises. This broadening of the donor energy distribution is largely sufficient to account for the experimentally observed magnetoresistance effects in n-type (Zn,Mn)Se with donor concentrations below the metal-insulator transition. [ABSTRACT FROM AUTHOR]