Rashba and Dresselhaus effects in 2D Pb-I-based perovskites

TL;DR

This study investigates how atomic displacements influence Rashba and Dresselhaus spin splitting in 2D lead-halide perovskites, revealing in-plane Pb displacements as key to these effects using density functional theory.

Contribution

It systematically analyzes the impact of symmetry-breaking atomic displacements on spin splitting in 2D perovskites, identifying specific displacement patterns that induce Rashba or Dresselhaus effects.

Findings

In-plane Pb displacements cause the strongest Rashba and Dresselhaus effects.

Displacement patterns determine the type and magnitude of spin splitting.

Spin textures differentiate between Rashba and Dresselhaus effects.

Abstract

Bulk hybride halide perovskites are governed by significant Rashba and Dresselhaus splitting. 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 are adopted where the organic compounds are replaced by Cs atoms. Disregarding possible distortions in the inorganic layers, results in structures with composition Cs$_{n+1}$Pb$_n$I$_{3n+1}$. Using the all-electron full-potential density-functional-theory code \texttt{exciting}, the impact of atomic displacement on the band structure is systematically studied for $n=1$, 2, 3 and $\infty$. 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.