Photomagnetic-Chiral Anisotropy mediated by Chirality-Driven Asymmetric Spin Splitting

TL;DR

This paper uncovers how chiral nanostructures in gold induce photomagnetic anisotropy by enhancing spin-orbit coupling and asymmetric spin splitting, linking chirality to spin dynamics and photomagnetic effects.

Contribution

It provides a first-principles theoretical explanation for photomagnetic-chiral anisotropy in chiral gold nanostructures, connecting chirality, spin-orbit coupling, and photomagnetic effects.

Findings

Chiral potentials enhance spin channel asymmetry.

Spin-orbit coupling links chirality to photomagnetic effects.

Chirality-driven spin flips generate opposing magnetic fields.

Abstract

Photo-magnetic effects (PMEs), intrinsic to transition metals, arises from the interaction between light-induced angu-lar momentum and electronic spin. These effects are suppressed in noble metals with high symmetry and electron density. Introducing chiral structures can induce photomagnetic-chiral anisotropy (PM-ChA) of metals by linking chirality and spin dynamics. However, a theoretical explain remains elusive. Here, we investigated the mechanism of PM-ChA in tetrahelix-stacked chiral nanostructured gold chains (CNACs) using first-principles calculations. Non-equilibrium Green's function calculations reveal that chiral potentials enhance spin channel asymmetry by amplify-ing spin-orbit coupling (SOC)-induced spin splitting. Real-time time-dependent density functional theory simulations further identify SOC as the bridge connecting chiral spintronics to PME, where chirality-driven spin flips from asymmetric geometries generate opposing photomagnetic fields in materials of different handedness. These findings are consistent with experimental observations in chiral nanostructured gold films and provide a theoretical instruction for design metallic spintronic devices.