Inverse Magnetoresistance Loops in Nearly Percolating Co–Ag Nanostructures and Two-Phase Model

概要

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We observed unusual inverse magnetoresistance (MR) loops in the transverse configuration for nearly percolating Co–Ag granular thin films deposited by a coevaporation technique onto a room-temperature glass substrate. When the substrate was heated above about 60°C during evaporation, the inverse MR loops disappeared and converted into normal loops. On the other hand, when the sample was annealed below about 120°C after deposition onto a room-temperature substrate, the inverse MR loops remained, whereas when annealed from about 120 to 300°C, the inverse MR loops were converted into "$\text{normal}+\text{inverse}$"-type loops and finally into totally normal loops when annealed above about 350°C. The unusual MR loops may have originated from magnetic nanostructures in nearly percolating Co–Ag granular films. A two-phase model incorporating uniaxial anisotropy, exchange interaction and spin-dependent scattering is presented, which is able to qualitatively explain some of the observed results.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-09-15