Ion oxidation mechanisms controlling the formation of barriers in magnetic tunnel junctions

Abstract

The oxidation mechanisms of the formation of thin insulating barriers in magnetic tunnel junctions are studied. The barriers are prepared by means of an oxidation technique using a highly dissociated low-energy (30–80 eV) ionized oxygen atom beam. The barrier formation is investigated using two independent in situ techniques, resistance and an optical reflectivity method. The oxidation depth varies from 1.5 to 1.9 nm depending on the initial ion energy in agreement with performed Monte Carlo simulations. Two different oxidation mechanisms (ion embedding and diffusion) are identified. The electrical and magnetotransport properties of the junctions are studied.