Application of spin-torque diode effect to the analysis of spin-transfer switching in MgO-based magnetic tunnel junctions

Abstract

Multilayers of buffer/Pt-Mn/Co-Fe/Ru/Co₆₀Fe₂₀B₂₀ (3.2 nm)/Mg (0.4 nm)/MgO (0.6 nm)/ Co₆₁Fe₇Ni₁₅B₁₅ (3 nm)/Ta/Ru is prepared on thermally oxidized Si substrates by UHV sputtering system (ANELVA C7100). The free layer Co-Fe-Ni-B has low magnetostriction, which is important characteristics for MRAM with high endurance for write/erase cycles. After annealing at 330degC, the film was patterned into 80 nm x 170 nm ellipsoids. The observed R-Hcurves showed sharp switching between low and high resistance states. The MR ratio was about 80% and resistance-area product was about 2 Omegam². STS effect for MTJ is applied to evaluate the spin-transfer switching.