Spin Dependence of Charge Dynamics and Group Velocity in Chiral Molecules

TL;DR

This paper investigates how spin-dependent electron dynamics in chiral molecules influence charge transport and group velocity, providing insights into the mechanisms behind chirality-induced spin selectivity (CISS) and its potential applications.

Contribution

The study introduces time-dependent quantum-transport simulations to analyze spin polarization and group velocity in chiral molecules, advancing understanding of CISS mechanisms.

Findings

Spin polarization is linked to spin-dependent group velocity.

Persistent spin polarization occurs with two leads connected.

Simulation results qualitatively match experimental magnetic-field signatures.

Abstract

Chiral molecules are known to preferentially select electrons with a particular spin state, an effect termed chirality-induced spin selectivity (CISS). In this work, the transient CISS dynamics in a chiral molecule are investigated through time-dependent quantum-transport simulations, an important step toward further understanding CISS and its application in devices such as magnetoresistive random access memories and spin-based quantum computers. We show that a nonzero spin polarization throughout the chiral molecule can be attributed to a spin-dependent group velocity of electrons. Contrary to the case where a chiral molecule is connected to a single lead, this spin polarization persists into the steady state when two leads are connected. We show that the simulated spin polarization qualitatively agrees with a reference experiment, as evidenced by the distinct magnetic-field signatures calculated from the spin polarization within a monolayer of chiral molecules.