Strain-induced gauge and Rashba fields in ferroelectric Rashba lead chalcogenide PbX monolayers (X = S, Se, Te)

TL;DR

This paper develops a theoretical framework to understand how strain affects the electronic and spin properties of ferroelectric Rashba monolayers, revealing strain-induced gauge fields and modifications to Rashba parameters.

Contribution

The authors derive an effective Hamiltonian that links strain to gauge fields and Rashba effects in PbX monolayers, advancing the understanding of strain engineering in 2D ferroelectric Rashba materials.

Findings

Strain induces gauge fields that shift the Rashba point.

Out-of-plane strain modifies the Rashba parameter.

Strain effects are equivalent to in-plane magnetic fields.

Abstract

One of the exciting features of two-dimensional (2D) materials is their electronic and optical tunability through strain engineering. Previously, we found a class of 2D ferroelectric Rashba semiconductors PbX (X = S, Se, Te) with tunable spin-orbital properties. In this work, based on our previous tight-binding (TB) results, we derive an effective low-energy Hamiltonian around the symmetry points that captures the effects of strain on the electronic properties of PbX. We find that strains induce gauge fields which shift the Rashba point and modify the Rashba parameter. This effect is equivalent to the application of in-plane magnetic fields. The out-of-plane strain, which is proportional to the electric polarization, is also shown to modify the Rashba parameter. Overall, our theory connects strain and spin splitting in ferroelectric Rashba materials, which will be important to understand the strain-induced variations in local Rashba parameters that will occur in practical applications.