Field dependence of magnetoresistance in half-metallic manganite

Abstract

Formular description of the magnetic field dependence of resistivity is of interest not only because of its theoretical importance, but also because it allows us to design magnetic-field-controlled devices. Using micromagnetic theory combined with charge carrier hopping and spin-polarized tunneling models, the magnetic field dependence of resistivity in half-metallic ferromagnet La 2/3 Sr 1/3 MnO 3 has been studied systematically. It has been shown that the resistivity is linearly dependent on magnetic field in a single grain. As for the resistivity of grain boundary (GB), namely the resistivity of spin transport across the boundary, it has an exponential relationship with magnetic field in the low-field region. Finally we give the analytical magnetoresistance formulas of polycrystalline, which agree well with the experimental results.