High-Temperature Thermal Magneto-Conductivity in Graphene Corbino

Measurement of thermal transport in strongly interacting and correlated electronic systems can reveal exotic new physics that may be elusive to electrical transport, such as neutral modes or emergent collective behavior. Graphene can host a strongly interacting quantum-critical Dirac fluid, where the thermal conductivity can deviate from the Wiedemann Franz law. Application of a magnetic field in the Dirac fluid can further enrich the thermal transport in the system as thermally drifting electron and hole motions differ from each other. In this talk, we present thermal magneto-conductivity measurements of graphene performed using Johnson noise thermometry and channel self-heating. In a Hall bar geometry, this measurement would not work due to hot spot formation near the contacts; however, the rotational symmetry of a Corbino geometry allows measurement of the radial component of electrical and thermal conductivity under a magnetic field. Under low applied magnetic field, we find the thermal magneto-conductivity changes sign as a function of density and magnetic field, while the electrical magneto-conductivity always remains negative. We discuss the thermal magneto-conductivity in the context of zero-field Wiedemann Franz deviations and hydrodynamics.