MTJ degradation in SOT-MRAM by self-heating-induced diffusion

In SOT-MRAM, the writing path is decoupled from the reading path and therefore considered robust against MgO breakdown in the MTJ. At operation, high current densities flow through the thin metallic SOT layer underneath the MTJ. We find that the SOT track is robust against electromigration, but we observe failure of the MTJ. A thorough chemical analysis indicates the activation of diffusion mechanisms that degrade the free layer and MgO tunnel barrier.