Colossal Orbital Current Induced by Gradient Oxidation for High‐Efficiency Magnetization Switching

Orbital angular momentum flow can be used to develop a low-dissipation electronic information device by manipulating the orbital current. However, efficiently generating and fully harnessing orbital currents is a formidable challenge. In this study, an approach is presented that induces a colossal orbital current by gradient oxidation in Pt/Ta to enhance spin-orbit torque (SOT) and achieve high-efficiency magnetization switching. The maximum efficiency of the SOT before and after the gradient oxidation of Ta is improved relative to that of Pt by ≈600 and 1200%, respectively. The large SOT originates from the colossal orbital current because of the orbital Rashba-Edelstein effect induced by the gradient oxidation of Ta. In addition, a large spin-to-charge conversion efficiency is observed in yttrium iron garnet/Pt/TaO