Tuning Rashba and Dresselhaus effect in 2D Pb-I-based perovskites

Huge spin-orbit coupling in combination with broken inversion symmetry leads to considerable Rashba and Dresselhaus splitting in hybride halide perovskites. This indicates that such effects will not only affect their optoelectronic properties but also those of their two-dimensional layered relatives. This work aims at understanding how different ways of symmetry breaking influence these effects in those materials. For this purpose, model structures with composition Cs_n+1Pb_nI_3n+1 are adopted where the organic compounds are replaced by Cs atoms. Using the all-electron full-potential density-functional-theory code exciting, the impact of atomic displacement on the band structure is systematically studied for n=1, 2, 3 and ∞. The displacement patterns that yield Rashba or Dresselhaus splitting are identified, and the amount of the splitting is determined as a function of displacement. Furthermore, the spin textures in the electronic states around the band gap are analyzed to differentiate between Rashba and Dresselhaus effects. This study reveals in-plane Pb displacements as the origin of the strongest effects.