Antiparallel spin polarizations as quadratic response in chiral systems

TL;DR

This paper theoretically investigates how chiral systems induce antiparallel spin polarization as a quadratic response to electric fields, revealing the role of microscopic parameters and challenging naive spin accumulation expectations.

Contribution

It introduces a theoretical framework for antiparallel spin polarization as a quadratic response in chiral systems using nonlinear Kubo formalism and real-time simulations.

Findings

Spatially inhomogeneous antiparallel spin polarizations are induced by a homogeneous AC electric field.

The microscopic parameters of chirality influence the spin polarization response.

The results challenge the naive expectation of spin accumulation from spin current.

Abstract

Chirality-dependent spin generation has attracted considerable attention in condensed matter physics. In this paper, we theoretically investigate antiparallel spin polarization as a chirality-dependent quadratic response, by using a finite chiral system composed of triangular prisms. Based on the nonlinear Kubo formalism and real-time simulations, we demonstrate that spatially inhomogeneous antiparallel spin polarizations are induced as a dissipative quadratic DC response to a homogeneous AC electric field. In particular, we elucidate role of microscopic parameters characterizing the handedness of chirality, and naive expectation of spin polarization as a consequence of spin accumulation of spin current.