Perpendicular magnetic tunnel junction (p-MTJ) spin-valves designed with a top Co2Fe6B2 free layer and a nanoscale-thick tungsten bridging and capping layer

Abstract

Recently, p-MTJ spin-valves with top Co2Fe6B2 free layers have been widely studied. They potentially experience crystallinity degradation in the face-centered-cubic (fcc) structure of the MgO tunneling barrier as a result of the diffusion of Ta atoms and a significant amount of Fe atoms from the Co2Fe6B2 free and pinned layers. A new design of the p-MTJ spin-valve using a nanoscale-thick W bridging and capping layer demonstrated the absence of significant crystallinity degradation in the fcc structure and showed a limited diffusion of Fe atoms, thus achieving a TMR ratio of similar to 143% at an ex-situ annealing temperature of 400 degrees C.