Tunnel Magnetoresistance Effect and the Magnetization Process of Gd Fe/Al oxide/Co/TbFe Junctions

Abstract

Magnetic tunnel junctions (MTJs) consisting of GdFe/Al oxide/Co/TbFe layers were fabricated. The GdFe and TbFe layers were perpendicularly magnetized, and the TbFe and Co layers were exchange-coupled with each other. Magnetoresistance (MR) curves were measured for MTJs with Co layers of various thicknesses while applying a field perpendicular to the film plane. The MR ratio showed a maximum of 12.1% when the Co layer thickness was 0.5 nm. Calculation using a noncontinuum model showed that the direction of the Co magnetization in the exchange-coupled film was perpendicular to the film plane when the thickness of the Co layer was less than 0.4 nm, which was consistent with measured magnetization curves as well as the results of simulation.