Theory of colossal magnetoresistance in R12xAxMnO3

A localization model comprising spin disorder and nonmagnetic randomness is presented to account\ud for novel magnetotransport properties in Mn oxides R12xAxMnO3. Localization length of electrons\ud as a function of magnetization is determined by means of the transfer matrix method. Including the\ud Coulomb interaction between electrons, the variable-range hopping resistivity is calculated as a function\ud of temperature and magnetic field. The resulting sharp resistivity peak near the Curie temperature and,\ud in particular, the magnitude of the colossal negative magnetoresistance are in good agreement with\ud experimental measurements