Hydrodynamic theory of chiral angular momentum generation in metals

TL;DR

This paper develops a hydrodynamic framework to understand how chiral electron systems with Weyl spin-orbit interaction generate orbital angular momentum in response to electric fields, revealing a global torque mechanism.

Contribution

It introduces a field-theoretic hydrodynamic theory for chiral metals, linking spin-orbit interaction to angular momentum generation and including effects of rotational viscosity.

Findings

Chiral nature induces bulk angular momentum via a global torque.

Steady state angular momentum depends on rotational viscosity.

Derived equations of motion for orbital angular momentum in chiral metals.

Abstract

We present a hydrodynamic theory to describe a chiral electron system with a Weyl spin-orbit interaction on a field-theoretic basis. Evaluating the momentum flux density as a linear response to a driving electric field, we derive an equation of motion for the orbital angular momentum. It is shown that the chiral nature leads to a dynamic bulk angular momentum generation by inducing a global torque as a response to the applied field. The steady state angular momentum is calculated taking account of rotational viscosity.