Magnetoresistance of (Co, Fe)-O and (Co, Fe)₇₅(Al, Si)₂₅-O Thin Films Evaporated in an Oxygen Atmosphere

Abstract

The structure, magnetization, and magnetoresistance were investigated for (Co, Fe)-O, and (Co, Fe)₇₅(Al, Si)₂₅-O thin films evaporated in an oxygen atmosphere with various incident angles α. The MR ratios at room temperature of Co-O Co₇₅Al₂₅-O and thin films prepared at α=0° and α=20° were about 2% and 8%. respectively. With increasing α, the MR ratio decreased. The temperature dependence of the resistivity and the dependence of magnetoresistance on the magnetization indicate that the observed magnetoresistance originates in spin-dependent tunneling of electrons through an insulator. Analysis of FT-IR spectra showed that Al₂O₃ existed in the Co₇₅Al₂₅-O thin film, which exhibited a large MR ratio.