Anisotropic Magnetoresistance and Weak Localization in Granular System Ni-MgO

Abstract

Magnetoresistive effect and electrotransport properties of Niх(MgO)100-х (x: 21-48 at.%) granular composites have been investigated. It is found that prepercolated composites (x < 24 at.%) do not exhibit magnetoresistive properties. After percolation threshold (x: 27-29 at.%) the composites exhibit isotropic negative magnetoresistance (-0,2 %) which has not tunneling nature. Also weak localization is realized in these samples at temperatures below 100 K. At high metal concentration (32 at.% < x) the composites exhibit anisotropic magnetoresistance.