Critical Current Reduction of Field-Free Perpendicular SOT-MTJ by STT Assist Using Micromagnetic Simulation

Field-free switching of perpendicular spin-orbit torque magnetic tunnel junction (p-SOT-MTJ) is investigated using micromagnetic simulation to evaluate the SOT critical current density (J$_{C, SOT}$). The spin-transfer torque (STT) can break the symmetry and ensure the deterministic switching of p-SOTMTJ without the external magnetic field. The decreasing SOT pulse width (t
SOT
) below 1 ns causes the significant increase of J$_{C,SOT}$. The increasing STT current density (J
STT
) can overcome the damping torque and reduce the J$_{C,SOT}$. For a short t
SOT
of 0.2 ns, the increase of STT current density (J
STT
) from 0.64 MA/cm
²
to 0.97 MA/cm$^{2}(V_{STT}$ from 0.2 V to 0.3 V) reduces the J$_{C,SOT}$ by 36%. As the spin Hall angle $(\theta_{SH})$ of SOT channels increases from 0.28 to 0.5, the J$_{C, SOT}$ can further be reduced by 46%.