Giant tunneling magnetoresistance up to 410% at room temperature in fully epitaxial Co∕MgO∕Co magnetic tunnel junctions with bcc Co(001) electrodes

Abstract

Fully epitaxial Co ( 001 ) ∕ Mg O ( 001 ) ∕ Co ( 001 ) magnetic tunnel junctions (MTJs) with metastable bcc Co(001) electrodes were fabricated with molecular beam epitaxy. The MTJs exhibited giant magnetoresistance (MR) ratios up to 410% at room temperature, the highest value reported to date. Temperature dependence of the MR ratio was observed to be very small compared with fully epitaxial Fe ∕ Mg O ∕ Fe and textured Co Fe B ∕ Mg O ∕ Co Fe B MTJs. The MR ratio of the Co ∕ Mg O ∕ Co MTJ showed larger bias voltage dependence than that of the epitaxial Fe ∕ Mg O ∕ Fe MTJs, which probably reflects the band structures of bcc Co and Fe for the k ‖ = 0 direction.