Orbital Current Boosting Magnetization Switching Efficiency in Metallic Superlattices

Orbitronics is an emerging domain within spintronics, and it is characterized by a rapid development of methods for utilizing orbital current. Metals with strong spin-orbit coupling have been effectively used to convert orbital current into orbital torque. This study introduces a metallic [W/Ti]₃ superlattice that uses orbital current to significantly enhance the magnetization switching efficiency. The enhancement in torque efficiency is demonstrated via spin-torque ferromagnetic resonance along with the extraction of damping-like (ξ_DL) and field-like spin-orbit torque (SOT) efficiencies. ξ_DL for superlattices is more than 100 times higher than that for Pt. As a result, the critical switching current density of the superlattice becomes two orders of magnitude lower than that of Pt. This is primarily attributed to the orbital current generated by the orbital Rashba–Edelstein effect at the W/Ti interface. The thickness of Ti and W layers is modulated to develop a novel approach to utilize orbital current for augmenting SOT efficiency and magnetization switching efficiency in superlattices. The findings of this study provide a basis for developing low-power-consumption memory devices and memory with controllable critical current density in SOT-magnetic random-access memory applications.