Emergence of large spin-charge interconversion at an oxidized Cu/W interface

Abstract

Spin-orbitronic devices can integrate memory and logic by exploiting spin-charge interconversion (SCI), which is optimized by design and materials selection. In these devices, interfaces are crucial elements as they can prohibit or promote spin flow in a device as well as possess spin-orbit coupling resulting in interfacial SCI. Therefore, investigation of interfaces in spin-orbitronic devices is important. Here, we study the origin of SCI in a Py/Cu/W lateral spin valve and quantify its efficiency. An exhaustive characterization of the interface between Cu and W electrodes uncovers the presence of an oxidized layer (WOx). We determine that the SCI occurs at the Cu/WOx interface with a temperature-independent interfacial spin-loss conductance of G(broken vertical bar broken vertical bar) approximate to 20 x 10(13) Omega(-1) m(-2) and an interfacial spin-charge conductivity sigma(SC) = -1600 Omega(-1)cm(-1) at 10 K (-800 Omega(-1) cm(-1) at 300 K). This corresponds to an efficiency given by the inverse Edelstein length lambda(IEE) = -0.8 nm at 10 K (-0.4 nm at 300 K), which is remarkably larger than in metal/metal and metal/oxide interfaces and bulk heavy metals. The large SCI efficiency at such an oxidized interface makes it a promising candidate for the magnetic readout in MESO logic devices.