Dissipation-enabled hydrodynamic conductivity in a tunable bandgap semiconductor

TL;DR

This study combines theory and experiments to demonstrate that dissipation-enabled hydrodynamic transport in bilayer graphene leads to a universal, temperature- and sample-independent conductivity at charge neutrality, bridging semiconductor physics and viscous electronics.

Contribution

It provides the first comprehensive experimental validation of dissipation-enabled hydrodynamic conductivity theory in a tunable bandgap semiconductor, specifically bilayer graphene.

Findings

Conductivity at neutrality is sample- and temperature-independent.

A single curve describes electron-hole conductivity away from neutrality.

Quantitative agreement achieved with only four fitting parameters.

Abstract

Electronic transport in the regime where carrier-carrier collisions are the dominant scattering mechanism has taken on new relevance with the advent of ultraclean two-dimensional materials. Here we present a combined theoretical and experimental study of ambipolar hydrodynamic transport in bilayer graphene demonstrating that the conductivity is given by the sum of two Drude-like terms that describe relative motion between electrons and holes, and the collective motion of the electron-hole plasma. As predicted, the measured conductivity of gapless, charge-neutral bilayer graphene is sample- and temperature-independent over a wide range. Away from neutrality, the electron-hole conductivity collapses to a single curve, and a set of just four fitting parameters provides quantitative agreement between theory and experiment at all densities, temperatures, and gaps measured. This work validates recent theories for dissipation-enabled hydrodynamic conductivity and creates a link between semiconductor physics and the emerging field of viscous electronics.