Magnetotransport effects in paramagnetic Gd$_x$Mn$_{1 -x}$S

The electrical resistance of Gd$_x$Mn$_{1-x}$ S solid solutions with $x = 0.1$, $0.15$, and $0.2$ has been measured at magnetic field $H = 0.8$ T and at zero magnetic field within the $100$ K${} < T < 550$ K temperature range. The magnetoresistance peak is observed above room temperature. On heating, the composition with $x = 0.2$ exhibits the change of magnetoresistance sign from positive to negative and the magnetoresistance peak near the transition to the magnetically ordered state. The experimental data are interpreted in the framework of the model involving the orbital ordering of electrons and the arising electrical polarization leading to the changes in the spectral density of states for electrons in the vicinity of the chemical potential in the applied magnetic field.