Unidirectional orbital magnetoresistance in light metal/ferromagnet bilayers

Abstract

We report the observation of a unidirectional magnetoresistance (UMR) that originates from the nonequilibrium orbital momentum induced by an electric current in a naturally oxidized Cu/Co bilayer. The orbital-UMR scales with the torque efficiency due to the orbital Rashba-Edelstein effect upon changing the Co thickness and temperature, reflecting their common origin. We attribute the UMR to orbital-dependent electron scattering and orbital-to-spin conversion in the ferromagnetic layer. In contrast to the spin-current induced UMR, the magnon contribution to the orbital-UMR is absent in thin Co layers, which we ascribe to the lack of coupling between low energy magnons and orbital current. The magnon contribution to the UMR emerges in Co layers thicker than about 5 nm, which is comparable to the orbital-to-spin conversion length. Our results provide insight into orbital-to-spin momentum transfer processes relevant for the optimization of spintronic devices based on light metals and orbital transport.

12 pages, 3 figures

References in corpus (16)

• Study of Intrinsic Spin Hall Effect and Orbital Hall Effect in 4d- and 5d- Transition Metals
• Giant Orbital Hall Effect in Transition Metals: Origin of Large Spin and Anomalous Hall Effects
• Efficient conversion of orbital Hall current to spin current for spin-orbit torque switching
• Large Unidirectional Magnetoresistance in a Magnetic Topological Insulator
• Giant orbital Hall effect and orbital-to-spin conversion in 3d, 5d, and 4f metallic heterostructures
• Observation of the Orbital Rashba-Edelstein Magnetoresistance
• Magnetization oscillations and waves driven by pure spin currents
• Orbital Rashba effect in surface oxidized Cu film
• Theory of unidirectional spin Hall magnetoresistance in heavy-metal/ferromagnetic-metal bilayers
• Electrical detection of magnetization reversal without auxiliary magnets
• Giant unidirectional magnetoresistance in topological insulator -- ferromagnetic semiconductor heterostructures
• Thickness dependence of unidirectional spin-Hall magnetoresistance in metallic bilayers
• Origin of threshold current density for asymmetric magnetoresistance in Pt/Py bilayers
• Large anomalous unidirectional magnetoresistance in a single ferromagnetic layer
• Current-induced torque originating from orbital current
• Theoretical Study of Extrinsic Spin-current Generation in Ferromagnets Induced by Anisotropic Spin-flip Scattering

Cited by in corpus (11)

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• Orbital Torque in Rare-Earth Transition-Metal Ferrimagnets
• Mitigation of Gilbert Damping in the CoFe/CuOx Orbital Torque System
• Quantum kinetic theory of quadratic responses
• Nonlinear longitudinal and transverse magnetoresistances due to current-induced magnon creation-annihilation processes
• Tunable spin and orbital torques in Cu-based magnetic heterostructures
• Nonlocal Electrical Detection of Reciprocal Orbital Edelstein Effect
• Estimation of spin-orbit torques in the presence of current-induced magnon creation and annihilation
• Proximity-induced nonlinear magnetoresistances on topological insulators
• Anatomy of torques from orbital Rashba textures: the case of Co/Al interfaces
• Evidence of orbital Hall current induced correlation in second harmonic response of longitudinal and transverse voltage in light metal-ferromagnet bilayers