Switching Rashba spin texture via interface with a ferroelectric compound

We study the microscopic factors controlling the switching of a Rashba(R) spin texture by switching the ferroelectric (FE) polarization of an underlying FE substrate. The spin polarization (SP) in R band depends on the direction of the intrinsic R electric dipole. Thus, an electric field changing the ferroelectic polarization should be able to reverse the Rashba SP. We study a heterojunction between FE PbTiO₃ (with TiO2 layers termination), and a R film of Pt, Pb, Rh, Ir, Au and Ag. We determine the role of FE slab thickness, passivation and atom relaxation on both the creation of R bands and SP switching. The FE polarization up (down) corresponds to the structural configuration with Ti above (below) O. Therefore, the R material, mainly interacts with Ti (O) for polarization up (Down). The R material then receives (donate) electrons for polarization up (down). Since Ti and O atoms mainly form the conduction and valence bands, respectively, we find that for up (down) polarization, R bands appear at the conduction (valence) bands. We find these R bands exhibit opposite helical spin texture for opposite ferroelectic polarization directions, allowing the possibility of control the SP direction with electric fields with an external electric field.