Harnessing Rashba spin-orbit interaction and related spintronic functionalities has traditionally relied on metallic surfaces or interfaces containing elemental heavy metals. Here, using first-principles calculations and $\mathrm{Cu}\left(001\right)\text{/}{\mathrm{WO}}_3\left(001\right)$ as a model heterostructure, we show that interfacing a light metal, Cu, with a band insulator, ${\mathrm{WO}}_3$, yields an interface state, which exhibits a robust Rashba spin splitting, arising from the interplay between linear and cubic Rashba effects. The spin splitting is driven by the strong spin-orbit coupling of W atoms and enabled by W-Cu orbital hybridization at the interface. The cubic Rashba contribution asymptotically grows with Cu thickness and can be explained in terms of cross-coupling between the vacuum/Cu and $\text{Cu/}{\mathrm{WO}}_3$ interfaces. This interfacial cross-coupling, however, diminishes at larger Cu thicknesses, allowing us to extract the intrinsic cubic Rashba parameter, which amounts to a giant value of $\approx$−1.93 $\mathrm{eV}{\AA }^3$. In contrast, the linear Rashba parameter is only weakly affected by this cross-coupling and varies from $\approx +0.3$ to $+0.49 \mathrm{eV}\AA$. We further show that sizable linear and cubic Rashba effects persist across several interface geometries and Cu surface orientations including (110) and (111). Our work identifies the $\text{Cu/}{\mathrm{WO}}_3$ interface as an interesting light metal/heavy-element-based oxide platform for exploring the rich spectrum of Rashba physics, including linear and nonlinear spin-orbit phenomena.

Close

PrevNext

View figure in article

• Rashba coupling
• Spintronics
• Complex oxides
• Heterostructures
• DFT+U