Switchable metal-to-half-metal transition at semi-hydrogenated graphene/ferroelectric interface

Tuning the half-metallicity of low-dimensional materials thanks to an electric field is particularly appealing for spintronic applications but typically requires ultra-high field hampering practical applications. Interface engineering has been suggested as an alternative practical mean to overcome this limitation and control the metal-to-half-metal transition. Here, we show from first-principles calculations that the polarization switching at the interface of semi-hydrogenated graphene (i.e., graphone) and ferroelectric PbTiO3 layer can reversibly tune a metal to half-metal transition in graphone. Using a simple Hubbard model, this is rationalized from interface atomic orbital hybridization, which also reveals as the origin of the high-quality screening of metallic graphone, preserving bulk-like stable ferroelectric polarization in the PbTiO3 film down to a thickness of two unit cells. These findings do not only open a new perspective to engineer half-metallicity at the interface of two-dimensional materials and ferroelectrics, but also identifies graphone as a powerful atomically thin electrode, which hold great promise to design ultrafast and high integration density information-storage devices.