Current-Driven Symmetry Breaking and Spin-Orbit Polarization in Chiral Wires

TL;DR

This study uses real-time ab initio simulations to show how current-driven symmetry breaking in chiral wires leads to spin and orbital polarization, impacting spintronics and chirality-induced effects.

Contribution

It introduces a nonperturbative real-time simulation approach to analyze spin and orbital dynamics in chiral systems under current.

Findings

Current flow breaks screw rotation and time-reversal symmetry.

Spin and orbital angular momenta emerge with a loss of linear momentum.

Mechanism has implications for spintronics and chirality-induced spin selectivity.

Abstract

The spin dynamics of electrons in chiral molecular systems remain a topic of intense interest, particularly regarding whether geometric chirality inherently induces spin polarization in current-carrying electrons. In this work, we employ ab initio real-time time-dependent density functional theory (rt-TDDFT) to directly simulate the interplay between charge current, spin, and orbital. This real-time tracking extends beyond perturbative treatments, and we analyze how nonequilibrium currents effectively lift the symmetry constraints of screw rotation and time-reversal symmetry. We find that the emergence of spin and orbital angular momenta is dynamically correlated with a concomitant loss of translational (linear) momentum, which we interpret as an intrinsic consequence of current-driven symmetry lowering. The implications of this mechanism for chirality-induced spin selectivity and spintronic device design are discussed.