Switchable Rashba Anisotropy in Two-dimensional Hybrid Organic-Inorganic Perovskite by Hybrid Improper Ferroelectricity

TL;DR

This study reveals a switchable Rashba anisotropy in a 2D hybrid organic-inorganic perovskite driven by ferroelectric polarization, enabling control over spin textures for potential spintronic applications.

Contribution

It uncovers a novel ferroelectric-induced Rashba anisotropy pseudo-rotation mechanism in 2D HOIPs, supported by theoretical modeling and experimental validation.

Findings

Large, tunable Rashba anisotropy in 2D HOIP.

Reversal of polarization inverts spin texture chirality.

Rashba ellipse axes interchange upon polarization switching.

Abstract

Two-dimensional (2D) hybrid organic-inorganic perovskites (HOIPs) are introducing new directions in the 2D materials landscape. The coexistence of ferroelectricity and spin-orbit interactions play a key role in their optoelectronic properties. We perform a detailed study on a recently synthesized ferroelectric 2D-HOIP, (AMP)PbI$_4$ (AMP = 4-aminomethyl-piperidinium). The calculated polarization and Rashba parameter are in excellent agreement with experimental values. We report a striking new effect, i.e., an extraordinarily large Rashba anisotropy that is tunable by ferroelectric polarization: as polarization is reversed, not only the spin texture chirality is inverted, but also the major and minor axes of the Rashba anisotropy ellipse in k-space are interchanged - a pseudo rotation. A $k \cdot p$ model Hamiltonian and symmetry-mode analysis reveal a quadrilinear coupling between the cation-rotation modes responsible for the Rashba ellipse pseudo-rotation, the framework rotation, and the polarization. These findings may provide new avenues for spin-optoelectronic devices such as spin valves or spin FETs.