Tuning Rashba–Dresselhaus effect with ferroelectric polarization at asymmetric heterostructural interface

The spin-orbit interaction (SOI) plays an essential role in materials properties, and controlling its intensity has great potential in the design of materials. In this work, asymmetric [(La_0.7Sr_0.3MnO₃)₈/(BaTiO₃)_t/(SrTiO₃)₂]₈ superlattices were fabricated on (001) SrTiO₃ substrate with SrO or TiO₂ termination, labelled as SrO-SL and TiO₂-SL, respectively. The in-plane angular magnetoresistance of the superlattices shows a combination of two- and four-fold symmetry components. The coefficient of two-fold symmetry component has opposite sign with current I along [100] and [110] directions for TiO₂-SL, while it has the same sign for SrO-SL. Detailed study shows that the asymmetric cation inter-mixing and ferroelectricity-modulated electronic charge transfer induce asymmetric electronic potential for SrO-SL with dominating Rashba SOI, and symmetric electronic potential for TiO₂-SL with dominating Dresselhaus SOI induced by BaTiO₃. This work shows that the Rashba and Dresselhaus SOIs are sensitive to the ferroelectric polarization in the asymmetric structure.