Effective electron coupling to phonon mechanical angular momentum in helical systems

Fuente: arXiv
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Hauptverfasser: Kato, Akihito, Yokoshi, Nobuhiko, Kishine, Jun-ichiro
Format: Preprint
Veröffentlicht: 2026
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author Kato, Akihito
Yokoshi, Nobuhiko
Kishine, Jun-ichiro
author_facet Kato, Akihito
Yokoshi, Nobuhiko
Kishine, Jun-ichiro
contents In chiral crystals, two types of phonon angular momenta have been introduced. One is crystal angular momentum (CAM) arising from the rotational or screw-rotational symmetry and the other is mechanical angular momentum (MAM) associated with the circular motion of atomic displacements about equilibrium positions. Recently, the electron--phonon coupling that respects the screw-rotational symmetry is derived, whereby the CAM between electrons and phonons is interconverted. Here, we show that, in addition to CAM, MAM can also be converted to the electronic degrees of freedom by deriving a second-order perturbative Hamiltonian proportional to phonon MAM. This finding highlights that the electronic motion is directly affected by phonon MAM, and consequently, that phonon degrees of freedom can play a crucial role in phenomena related to electronic orbital and spin polarizations.
format Preprint
id arxiv_https___arxiv_org_abs_2604_02716
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Effective electron coupling to phonon mechanical angular momentum in helical systems
Kato, Akihito
Yokoshi, Nobuhiko
Kishine, Jun-ichiro
Materials Science
In chiral crystals, two types of phonon angular momenta have been introduced. One is crystal angular momentum (CAM) arising from the rotational or screw-rotational symmetry and the other is mechanical angular momentum (MAM) associated with the circular motion of atomic displacements about equilibrium positions. Recently, the electron--phonon coupling that respects the screw-rotational symmetry is derived, whereby the CAM between electrons and phonons is interconverted. Here, we show that, in addition to CAM, MAM can also be converted to the electronic degrees of freedom by deriving a second-order perturbative Hamiltonian proportional to phonon MAM. This finding highlights that the electronic motion is directly affected by phonon MAM, and consequently, that phonon degrees of freedom can play a crucial role in phenomena related to electronic orbital and spin polarizations.
title Effective electron coupling to phonon mechanical angular momentum in helical systems
topic Materials Science
url https://arxiv.org/abs/2604.02716