Interfacial Orbital Rashba Edelstein Effect Identified in CoO/Cu/Pt Trilayers

We investigate the generation of orbital angular momentum currents at engineered Cu-oxide interfaces using CoO/Cu/Pt thin-film trilayers. Angular-dependent magnetoresistance measurements on samples with varying Cu interlayer thickness reveal systematic changes in both longitudinal and transverse resistance components, including a sign inversion of the signal. By systematically varying the Cu interlayer thicknesses, we disentangle the spin and orbital contributions to the magnetoresistive response. Our results show that large orbital currents originate from the interfacial orbital Rashba-Edelstein effect due to the presence of the Cu-O bonds at the CoO/Cu interface. Unlike previously studied CoO/Cu bilayers that rely on uncontrolled natural oxidation, our trilayer geometry enables reproducible and stable orbital-current generation at ambient conditions. Our results identify Cu-oxide interfaces as efficient sources of orbital angular momentum and clarify the microscopic mechanism underlying orbital current generation. Consequently, this work establishes a well-defined materials platform for all-orbitronic devices that does not require relativistic spin-orbit coupling or orbital-spin interconversion processes.