Colossal magnetoresistance of the variable range hopping regime in the manganites

Abstract
Evidence for variable range hopping (VRH) is presented in resistivity measurements in thin films and bulk samples of different substituted x=0.3 manganese perovskites. The necessity to modify the Mott VRH model is shown and we have developed a model based on magnetic localization hopping, which is used to reproduce temperature and field dependence of resistivity in these mixed-valence compounds.