Emergence of radial Rashba spin-orbit fields in twisted van der Waals heterostructures

Rashba spin-orbit coupling is a quintessential spin interaction appearing in virtually any electronic heterostructure. Its paradigmatic spin texture in the momentum space forms a tangential vector field. Using first-principles investigations, we demonstrate that in twisted homobilayers and heteromultilayers, the Rashba spin texture can be predominantly radial, parallel to the momentum. Specifically, we study four experimentally relevant structures: twisted bilayer graphene (Gr), twisted bilayer WSe 2 , and twisted multilayers WSe 2 / Gr / WSe 2 and WSe 2 / Gr / Gr / WSe 2 . We show that the Rashba spin texture in such structures can be controlled by an electric field, allowing to tune it from radial to tangential. Such spin-orbit engineering should be useful for designing spin -charge conversion and spin-orbit torque schemes, as well as for controlling correlated phases and superconductivity in van der Waals materials.