Grain Size Effect on Electrical Conductivity and Giant Magnetoresistance of Bulk Magnetic Polycrystals

By solving the Boltzmann transport equation and considering the spin-dependent grain boundary scattering, the distribution of electrons in grains and the electrical transport properties in the applied magnetic field are studied. With regard to the dominant influence of grain boundary scattering which is taken as a boundary condition for the electrical transport, the grain size-dependent electrical conductivity is investigated. In addition, the reorientation of the relative magnetization between grains brings the change of the electron spin when the magnetonanocrystalline material is subjected to the magnetic field, resulting in the remarkable giant magnetoresistance effect.