Scaling description of positive magnetoresistivity in doped dilute magnetic semiconductors

The effect of a large positive magnetoresistance (MR) in Zn1−xMnxSe:Cl materials in the hopping regime is studied experimentally and theoretically. A possible mechanism of this effect has been recently suggested [Nenashev et al., Phys. Rev. B 88 (2013) 115210] [4] based on the increase of energy disorder in the distribution of dopant levels caused by the exchange interaction between magnetic Mn atoms and the electrons localized on nonmagnetic Cl impurities. In the current work we confirm this mechanism experimentally by comparison between the MR in samples with finite Mn content x and the MR in a sample with x=0. At x=0, a negative MR is observed, while at finite x a large positive MR is evidenced with the dependence on magnetic field similar to that of the macroscopic magnetization, confirming the suggested MR mechanism at finite x. Scaling description of the positive MR [Nenashev et al., Phys. Rev. B 88 (2013) 115210] [4] has been suggested so far only for the case of the nearest-neighbor-hopping or Mott variable-range-hopping regimes. In the current work, we present experimental data to analyze the underlying transport regime and extend the scaling description for the Efros-Shklovskii variable-range-hopping regime, in which many-particle Coulomb interactions play a decisive role for the distribution of electron energies on dopant atoms.