Toward a ferroelectric control of Rashba spin-orbit coupling: Bi onBaTiO3(001)from first principles

As demonstrated conceptually by first-principles calculations, the Rashba spin splitting in the $6p$ states of a Bi adlayer on ${\text{BaTiO}}_{3}(001)$ can be manipulated by the electric polarization in the ferroelectric substrate. Although this spin-electric effect is moderate, with a relative change in the splitting of about 5%, the absolute splitting of about $0.24\text{ }{\text{\AA{}}}^{\ensuremath{-}1}$ is unmatched. Further, the occupied $6p$ surface states display an anisotropic dispersion and deviate significantly from the free-electron model of the Rashba effect. Our findings may pave a route for spin-electronic devices.