Observation of Electronic Viscous Dissipation in Graphene Magneto-thermal Transport

Dr. Jonah Weissman, Institute of Applied Physics, HUJI

Thursday, Nabuary 15,  2026, 11:00 AM, Los Angeles Seminar Room

Hydrodynamics describes the collective transport of strongly-interacting particles. Due to enhanced
electron-electron interactions at elevated temperatures, the behavior of electrons in clean graphene can
be depicted as a hydrodynamic flow of charge. In this new regime, the well-known rules of Ohmic
transport no longer apply, necessitating the consideration of collective electron dynamics. In particular,
the hydrodynamic analogues of Joule heating and thermal transport require consideration of the
electronic viscosity and associated energy dissipation, but remain unexplored. In this work, we probe
graphene via thermal transport measurement in small magnetic fields and find an unexpected
enhancement of cooling in Corbino geometries. We construct a theory that identifies the origin of this
effect in viscous dissipation of the electron fluid, enabling a new measurement of the electronic viscosity
and underlying microscopic thermal and electrical conductivities. This reveals the Lorenz ratio of the
graphene electronic fluid, which is shown to be strongly suppressed away from charge neutrality
compared to the Wiedemann-Franz value, in agreement with longstanding expectations for the
hydrodynamic regime. Our results demonstrate viscous electronic heating in an electron fluid, offering a
new, transport-based methodology for identifying hydrodynamic states in other material systems, and
providing insight for thermal management in electronic hydrodynamic devices. Time permitting, I will
discuss our new approach to low-dimensional thermal transport and future possibilities.