Spintronics in two-dimensional surface conducting diamond

When hydrogen-terminated diamond surfaces are exposed to air, electrons are transferred from the diamond into an absorbed water layer resulting in a sub-surface hole accumulation layer and a high p-type surface conductivity. This allows high hole sheet densities to be achieved and has led to significant interest for chemical and biological sensor applications. Through the preparation of high-quality, low disorder hydrogenated surfaces, surface conducting diamond devices can be prepared with metallic conductivity permitting the study of magnetotransport effects at temperatures as low as 50 mK.

Magnetotransport measurements have revealed the presence of phase coherent backscattering effects, in the form of weak localisation and weak anti-localisation. By exploring quantum transport in fabricated diamond devices, we have shown that the hole accumulation layer forms a two-dimensional system with a strong spin-orbit interaction (Edmonds et al., 2015). Surface conducting diamond is a spin-3/2 p-type semiconductor, offering interesting spin properties that differ to those of graphene and other two-dimensional systems. We are developing this project through a number of avenues that seek to explore these properties and to engineer devices that permit the control of spin as a route towards carbon-based semiconductor spintronics.