Tunnel-type GMR in CoAlO insulated granular system — Its oxygen-concentration dependence

CoAlO thin films, with network-like nano granular structure consisting of Co based magnetic and metallic grains and A1 2 O 3 based nonmetallic intergrains, were fabricated by Ar + O 2 reactive sputtering. Giant magnetoresistances (GMR) were observed. From the experiments on oxygen concentration dependence of GMR, electrical resistivity and microstructure, it was confirmed that spin dependent tunneling was responsible for the GMRs.