Enhancement of spin-charge current interconversion by oxidation of rhenium

We have demonstrated enhancement of the spin-charge current interconversion by oxidation of rhenium (Re). Although amorphous rhenium oxide (ReOX) is electrically conductive, the spin–orbit torque efficiency measured by spin-torque ferromagnetic resonance is 0.074, and 37 times larger than the pure Re case whose amplitude is 0.002. Furthermore, we have also found that the values of the damping-like and field-like torque efficiencies are 0.030 and −0.052, respectively. These values are comparable with those for conventional spin–orbit materials such as Pt or Ta, suggesting that ReOX is a candidate material for spintronics devices. THz-time domain spectroscopy was performed to confirm the inverse spin-charge current conversion process in ReOX.