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, such as the magnetoelectric spin-orbit (MESO) logic, 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. 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 (WO${}_x$). We determine that the SCI occurs at the Cu/WO${}_x$ interface with a temperature-independent interfacial spin-loss conductance of $G_{||}\approx$ 20 $\times$ 10${}^{13}{\Omega }^{-1}{m}^{-2}$ and an interfacial spin-charge conductivity ${\sigma }_{SC}=-$1610 ${\Omega }^{-1}c{m}^{-1}$ at 10 K ($-$830 ${\Omega }^{-1}c{m}^{-1}$ at 300 K). This corresponds to an efficiency given by the inverse Edelstein length ${\lambda }_{IEE}=-$0.76 nm at 10 K ($-$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 is a promising candidate for the magnetic readout in MESO logic devices.

arXiv comment11 pages, 3 figures, and Supplemental Material

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