Difference between angular momentum and pseudoangular momentum

TL;DR

This paper clarifies the distinction between angular momentum and pseudoangular momentum in condensed matter physics, emphasizing the importance of this difference for understanding angular momentum transfer in spintronics.

Contribution

It demonstrates, using Noether's theorem, that orbital angular momenta of phonons and magnons are actually pseudoangular momenta, clarifying their conceptual roles.

Findings

Orbital angular momenta of phonons and magnons are pseudoangular momenta.

The distinction impacts understanding of angular momentum transfer in spintronics.

Highlights the importance of conceptual clarity in condensed matter physics.

Abstract

In condensed matter systems it is necessary to distinguish between the momentum of the constituents of the system and the pseudomomentum of quasiparticles. The same distinction is also valid for angular momentum and pseudoangular momentum. Based on Noether's theorem, we demonstrate that the recently discussed orbital angular momenta of phonons and magnons are pseudoangular momenta. This conceptual difference is important for a proper understanding of the transfer of angular momentum in condensed matter systems, especially in spintronics applications.