Electrical transport properties of (Co_xAl_(1-x))_2O_(3-v) oxide magnetic semiconductor and corresponding Co-Al_2O_3 granular films

摘要

(Co_xAl_(1-x))_2O_(3-v) oxide magnetic semiconductor films were synthesized by introducing an impurity band in the insulating Al_2O_3 band gap, and the corresponding granular films were obtained by annealing. For both kinds of films, their electrical transport properties are well described by spin dependent variable range hopping mechanism instead of the usually expected intergrain tunnelling. The magnetoresistance was also discussed.