Controllable charge-spin conversion by Rashba-Edelstein effect at Cu/Ta interface

Abstract

The Rashba-Edelstein effect typically originates from inversion symmetry breaking at an interface that allows charge to spin conversion efficiency comparable to or larger than the SHE. Its potential value is in converting charge current into spin current. Here, we demonstrate experimentally an efficient charge to spin conversion at a Cu/Ta Rashba interface. We exploit spin-torque ferromagnetic resonance to detect a spin current from Cu/Ta interface into adjacent FeNi magnetic layer. The Ta thickness dependence of charge to spin conversion efficiency unambiguously ascribed that interface effect caused FeNi magnetization to precess by generating nonzero spin current that exerts torques rather than bulk effect. The possibility of controllable charge-spin conversion efficiency at room temperature opens another route for modulating the charge to spin conversion by interface engineering.