Electric field and strain induced Rashba effect in hybrid halide perovskites

TL;DR

This study uses first principles calculations to show how electric fields and strain can tune the Rashba effect in hybrid halide perovskites, with implications for spintronic applications and material design.

Contribution

It demonstrates the tunability of Rashba splitting in hybrid perovskites through electric fields, strain, and chemical substitution, providing pathways for material engineering.

Findings

Rashba splitting increases with organic cation alignment and electric polarization.

Chemical substitution affects Rashba splitting by altering polar distortion patterns.

Polar phases with significant Rashba splitting can be stabilized at room temperature via strain.

Abstract

Using first principles density functional theory calculations, we show how Rashba-type energy band splitting in the hybrid organic-inorganic halide perovskites APbX$_3$ (A=CH$_3$NH$_3^+$, CH(NH$_2$)$_2^+$, Cs$^+$ and X=I, Br) can be tuned and enhanced with electric fields and anisotropic strain. In particular, we demonstrate that the magnitude of the Rashba splitting of tetragonal (CH$_3$NH$_3$)PbI$_3$ grows with increasing macroscopic alignment of the organic cations and electric polarization, indicating appreciable tunability with experimentally-feasible applied fields, even at room temperature. Further, we quantify the degree to which this effect can be tuned via chemical substitution at the A and X sites, which alters amplitudes of different polar distortion patterns of the inorganic PbX$_3$ cage that directly impact Rashba splitting. In addition, we predict that polar phases of CsPbI$_3$ and (CH$_3$NH$_3$)PbI$_3$ with $R3c$ symmetry possessing considerable Rashba splitting might be accessible at room temperature via anisotropic strain induced by epitaxy, even in the absence of electric fields.