Negative Magnetoresistivity in Tl4Se3S Crystals

 The temperature and magnetic field dependencies of the magnetoresistivity of Tl4Se3S crystals have been measured in the temperature region of 195-310 K at magnetic fields up to 1.4 T. The magnetoresistivity is observed to exhibit negative values at all measured temperatures. Increasing the magnetic field intensity leads to larger values of negative magnetoresistivity. The magnetoresistivity as a function of applied field was described by the Khosla-Fischer model for spin scattering of carriers in an impurity band. The temperature dependence of magnetoresistivity has revealed the existence of paramagnetic–ferromagnetic and ferromagnetic–paramagnetic phase transitions at 270 and 220 K, respectively. The existence of these transitions is attributed to the domination of localized spin scattering (magnetic scattering) in the temperature region of 220-270 K and the domination of thermal lattice scattering in the remaining temperature regions.