Switching performance comparison between conventional SOT and STT-SOT write schemes with effect of shape deformation

We demonstrate the effect of shape deformation in spin–orbit torque magnetoresistive random access memory (SOT-MRAM) based on micromagnetic simulation by generating 1000 randomly deformed samples using the exponentially decaying autocorrelation function. The conventional in-plane magnetic field-assisted SOT write scheme and the recently proposed spin-transfer torque-spin-orbit torque (STT-SOT) hybrid write scheme were simulated and compared with the effect of the Gilbert damping constant (α) considered in the presence and the absence of the Dzyaloshinskii–Moriya interaction (DMI). We found that shape deformation of the MTJ can result in write failure or degradation of the switching time. To compensate the device-to-device performance variation induced by the shape deformation, the condition of high α and the presence of the DMI is desired for the magnetic field-assisted write scheme. The STT-SOT shows slight improvement in the switching performance for larger α and the presence of DMI while it retains 100% switching probability even with small α regardless of the DMI.