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.