Spin-Dependent Electronic Transport in Granular Ferromagnets

Abstract

We report a comparative study of the spin-dependent electronic transport in two types of granular ferromagnetic systems: ferromagnet metal (Ni-Ag, Co-Ag) and ferromagnet insulator (Ni-Si${\mathrm{O}}_{2}$, Co-Si${\mathrm{O}}_{2}$). Both systems demonstrate remarkably similar magnetoresistive behavior of comparable magnitude: negative isotropic magnetoresistance below the ferromagnet percolation threshold and the anisotropic magnetoresistance above.