Observation of the out-of-plane orbital antidamping-like torque

The out-of-plane antidamping-like orbital torque fosters great hope for high-efficiency spintronic devices. Here we report experimentally the observation of out-of-plane antidamping-like torque that could be generated by z-polarized orbital current in ferromagnetic-metal/oxidized Cu (CuO) bilayers, which is presented unambiguously by the magnetic field angle dependence of the spin-torque ferromagnetic resonance signal. The CuO thickness dependence of the orbital torque ratios highlights that the interfacial effect would be responsible for the generation of orbital current. Besides that, the CuO thickness dependence of the damping parameter further proves the observation of antidamping-like torque. This result contributes to enriching the orbital-related theory of the generation mechanism of the orbital torque.