Spin-orbit effects at chiral surfaces

TL;DR

This paper theoretically investigates spin-orbit effects on chiral and achiral two-dimensional lattices, revealing distinct spin textures and the inversion of the longitudinal spin component in chiral systems, with a heuristic model explaining these phenomena.

Contribution

It introduces a theoretical analysis of spin textures in chiral versus achiral lattices and presents a heuristic model for understanding spin polarization inversion.

Findings

Achiral hexagonal lattice has two non-zero spin components.

Chiral lattice exhibits all three non-zero spin components.

Longitudinal spin component inverts between enantiomorphs.

Abstract

Two-dimensional hexagonal and oblique lattices were investigated theoretically with the aim of observing differences in the spin expectation values between chiral and achiral systems. The spinresolved band structures were derived from the energy eigenvalues and eigenfunctions of a Hamiltonian that includes the lattice potential and the spin-orbit interaction. The spin texture of the achiral hexagonal system was shown to have two non-zero components of the spin polarisation, whereas all three components were calculated to be non-zero for the chiral system. The longitudinal component, found to be zero in the achiral lattice, was observed to invert between the enantiomorphs of the chiral lattice. A heuristic model was introduced to discern the origin of this inverting spin polarisation by considering the dynamics of an electron in chiral and achiral lattices. This model was further used to demonstrate the change in magnitude of the spin polarisation as a function of the lattice parameters and an electric field perpendicular to the lattice.