Orbital Rashba effect in surface oxidized Cu film

Abstract

Recent experimental observation of unexpectedly large current-induced spin-orbit torque in surface oxidized Cu on top of a ferromagnet suggested a possible role of the orbital Rashba effect (ORE). With this motivation, we investigate the ORE from first principles by considering an oxygen monolayer on top of a Cu(111) film. We show that surface oxidization of Cu film leads to gigantic enhancement of the ORE for states near the Fermi surface. The resulting chiral orbital texture in the momentum space is exceptionally strong, reaching $\sim 0.5\hslash$ in magnitude. We find that resonant hybridization between O $p$-states and Cu $d$-states is responsible for the emergence of the ORE. We demonstrate that application of an external electric field generates huge orbital Hall current, which is an order of magnitude larger than the spin Hall current found in heavy metals. This implies that "orbital torque" mechanism may be significant in surface oxidized Cu/ferromagnet structures. It also encourages experimental verification of the orbital texture in surface oxidized Cu through optical measurements such as angle-resolved photoemission spectroscopy.

References in corpus (7)

• Maximal Rashba-like spin splitting via kinetic energy-driven inversion symmetry breaking
• Maximally Localized Wannier Functions within the FLAPW formalism
• Theory of Current-Induced Angular Momentum Transfer Dynamics in Spin-Orbit Coupled Systems
• Microscopic Theory of Rashba Interaction in Magnetic Metal
• Intrinsic orbital and spin Hall effects in monolayer transition metal dichalcogenides
• Photoinduced Rashba spin to charge conversion via interfacial unoccupied state
• Current-induced torque originating from orbital current

Cited by in corpus (1)

• Orbitronics: Orbital Currents in Solids