Realization of a universal hydrodynamic semiconductor in ultra-clean dual-gated bilayer graphene

Abstract

Hydrodynamic electronic transport is of fundamental interest due to its presence in strongly correlated materials and connections to areas outside of condensed matter physics; its study will be facilitated by identifying ambipolar hydrodynamic materials in which collisions between thermally activated electrons and holes determine conductivity. Here we present a comprehensive experimental and theoretical study of hydrodynamics in bilayer graphene, and consider the effects of an induced bandgap. For zero bandgap, conductivity at charge neutrality is temperature-independent; its magnitude determined by Planckian dissipation. With a bandgap, conductivity at charge neutrality collapses onto a universal curve. These results demonstrate that electron-hole collision limited transport in bilayer graphene can be readily detected at room temperature using straightforward DC conductivity measurements, providing an easily accessible platform for hydrodynamic investigations