Viscometry of electron fluids from symmetry

TL;DR

This paper introduces a symmetry-based viscometry method to measure multiple viscosity components in electron fluids, enabling detection of rotational dissipation in isotropic metals.

Contribution

It develops a symmetry-informed viscometry technique applicable to both isotropic and anisotropic electron fluids, enhancing robustness against boundary and ballistic effects.

Findings

Proposes a symmetry-based viscometry method for electron fluids.

Identifies the potential to detect rotational dissipation in isotropic metals.

Demonstrates applicability to dihedral symmetry in 2D crystals.

Abstract

When electrons flow as a viscous fluid in anisotropic metals, the reduced symmetry can lead to exotic viscosity tensors with many additional, nonstandard components. We present a viscometry technique that can, in principle, measure the multiple dissipative viscosities allowed in isotropic and anisotropic fluids alike. By applying representation theory to exploit the intrinsic symmetry of the fluid, our viscometry is also exceptionally robust to both boundary complications and ballistic effects. We present the technique via the illustrative example of dihedral symmetry, relevant in this context as the point symmetry of 2D crystals. Finally, we propose a present-day realizable experiment for detecting, in a metal, a novel hydrodynamic phenomenon: the presence of rotational dissipation in an otherwise isotropic fluid.