First-principles prediction of chiral-phonon-induced orbital accumulation

TL;DR

This study uses first-principles calculations to demonstrate that chiral phonons can induce orbital and spin accumulations in metals, highlighting the role of orbital character and electron-phonon interactions.

Contribution

It introduces a first-principles method to evaluate electronic responses to chiral phonons, emphasizing orbital effects over spin-orbit coupling.

Findings

Coherent chiral lattice motion generates orbital accumulation.

Spin accumulation occurs via spin-orbit coupling but is smaller.

Light transition metals are promising for chiral-phonon-driven orbitronics.

Abstract

Chiral phonons offer a route to transfer angular momentum without relying on magnetic order, but their electronic response in metals remains poorly understood from perspectives beyond spin-based scenarios. Using first-principles calculations, we show that coherent chiral lattice motion generates orbital accumulation and, through spin-orbit coupling, a smaller accompanying spin accumulation. Our approach evaluates orbital and spin expectation values directly from strain perturbed ab initio Hamiltonians in the long-wavelength limit, where the phonon perturbation is represented by symmetry adapted circular lattice distortions. We show that the response is controlled mainly by orbital character, near-degeneracies, and electron-phonon coupling, rather than by spin-orbit coupling alone. These results identify light transition metals as promising platforms for chiral-phonon-driven orbitronics.