Giant spin-orbit torque and nonreciprocal charge transport in two-dimensional hole gas on the hydrogen-terminated diamond surface

Efficient charge-to-spin conversion, which stems from the Rashba-type spin-orbit interaction, is one of the most promising spintronics functionalities in two-dimensional carrier systems. A two-dimensional hole gas (2DHG) is created at the surface of hydrogen-terminated (H-) diamond, where the strong Rashba-type spin-orbit coupling is induced, albeit it consists of only light elements as hydrogen and carbon. In this study, the charge-to-spin conversion and nonreciprocal charge transport owing to the Rashba-Edelstein effect in the 2DHG were investigated. The charge-to-spin conversion efficiency in the 2DHG is estimated to be equivalent to that of Pt and LaAlO3 / SrTiO3. The magnitude of non-reciprocal charge transport was comparable to that of WTe2 and Si. These results pave the way of spin generation by using light-element-based materials.