Enhanced Spin Torque Efficiency in Amorphous CoGe with Oxide Interlayers

One of the leading candidates for next-generation magnetic memory applications is the class of devices employing Spin-Orbit Torque (SOT) where a spin generating layer exerts a switching torque on a magnetic layer. The observation of large anomalous hall effect in amorphous FeSi (a-Fe-Si) and large spin torque efficiency generated interest in amorphous 3d metals alloyed with semiconductors like silicon and germanium. We sputtered various compositions of amorphous CoGe (a-Co-Ge) with Ni₈₁Fe₁₉ and measured spin torque efficiencies with spin-torque ferromagnetic resonance and second harmonic voltage measurements. We also explored the possibility of enhancing the spin torque efficiency by introducing various thin oxide layers between a-Co-Ge and Ni₈₁Fe₁₉.