Electronic control of phonon mechanical angular momentum in chiral systems

Determine whether electronic degrees of freedom can control phonon mechanical angular momentum (MAM) in chiral crystals and molecules.

Background

The paper derives an effective second-order electron–phonon interaction in a helical crystal that is directly proportional to the phonon mechanical angular momentum (MAM), showing a direct pathway for transferring angular momentum between phonons and electrons. This complements prior work focused on crystal angular momentum (CAM) and highlights potential implications for electronic orbital and spin polarizations in chiral systems.

In the concluding remarks, the authors explicitly defer to future studies both the extension of their results to general chiral crystals and molecules and the exploration of whether phonon MAM can be controlled electronically. The latter constitutes a concrete unresolved question about the feasibility of manipulating phonon MAM via electronic means in broader classes of chiral materials.

References

Extension of our result to the general chiral crystals and molecules and exploration of the possibility of the electronic control of the phonon MAM will be left for future studies.

— Effective electron coupling to phonon mechanical angular momentum in helical systems  (2604.02716 - Kato et al., 3 Apr 2026) in Section 4 (Concluding Remarks)