# Hydrodynamic flows of non-Fermi liquids: magnetotransport and bilayer drag

## TL;DR

This paper develops a hydrodynamic framework for non-Fermi liquid 2D electron systems, analyzing magnetoresistance and Coulomb drag, with applications to quantum Hall states and composite fermions.

## Contribution

It introduces a hydrodynamic approach to non-Fermi liquids, deriving magnetoresistance and Coulomb drag formulas applicable to systems lacking Galilean invariance.

## Key findings

- Magnetoresistance depends solely on electronic viscosity under certain conditions.
- Derived Coulomb drag transresistance for double-layer non-Fermi liquids.
- Applied results to quantum Hall states with composite fermions, aligning with experimental data.

## Abstract

We consider a hydrodynamic description of transport for generic two dimensional electron systems that lack Galilean invariance and do not fall into the category of Fermi liquids. We study magnetoresistance and show that it is governed only by the electronic viscosity provided that the wavelength of the underlying disorder potential is large compared to the microscopic equilibration length. We also derive the Coulomb drag transresistance for double-layer non-Fermi liquid systems in the hydrodynamic regime. As an example, we consider frictional drag between two quantum Hall states with half-filled lowest Landau levels, each described by a Fermi surface of composite fermions coupled to a $U(1)$ gauge field. We contrast our results to prior calculations of drag of Chern-Simons composite particles and place our findings in the context of available experimental data.