Dependence of tunnel magnetoresistance on ferromagnetic electrode materials in MgO-barrier magnetic tunnel junctions

摘要

We investigated the relationship between the tunnel magnetoresistance (TMR)ratio and the electrode structure in MgO-barrier magnetic tunnel junctions(MTJs). The TMR ratio in a MTJ with Co40Fe40B20 reference and free layersreached 355% at the post-deposition annealing temperature of Ta=400 degree C.When Co50Fe50 or Co90Fe10 is used for the reference layer material, no high TMRratio was observed. The key to have high TMR ratio is to have highly oriented(001) MgO barrier/CoFeB crystalline electrodes. The highest TMR ratio obtainedso far is 450% at Ta = 450 degree C in a pseudo spin-valve MTJ.