Interface-Induced Conservation of Momentum Leads to Chiral-Induced Spin Selectivity

TL;DR

This paper demonstrates that interface structure and momentum conservation are key to chiral-induced spin selectivity, showing how extended interfaces lead to spin polarization in electron transmission through a helix with spin-orbit coupling.

Contribution

It reveals that interface-induced momentum conservation is crucial for spin selectivity, providing a new understanding of mechanisms behind chiral-induced spin effects.

Findings

Spin selectivity depends on interface width.

Single-point couplings do not produce polarization.

The mechanism is robust against static disorder.

Abstract

We study the non-equilibrium dynamics of electron transmission from a straight waveguide to a helix with spin-orbit coupling. Transmission is found to be spin-selective and can lead to large spin polarizations of the itinerant electrons. The degree of spin selectivity depends on the width of the interface region, and no polarization is found for single-point couplings. We show that this is due to momentum conservation conditions arising from extended interfaces. We therefore identify interface structure and conservation of momentum as crucial ingredients for chiral-induced spin selectivity, and confirm that this mechanism is robust against static disorder.