(Invited) Flow of Charge and Heat in Ultra-Clean Graphene

Abstract

Over the past two decades our understanding of the charge and heat transport properties of graphene has evolved progressively as the quality of graphene devices improved. In this talk, I shall present some new experimental result on the electrical and thermal transport measurements in graphene devices of unprecedented electrical mobility (> 1 million cm2/V.s). We show that the transport in such graphene devices is limited by intrinsic acoustic phonons and their scattering with electrons, rather than charged impurities – which is the case in conventional disordered graphene devices. This manifests in a rather striking violation of the Wiedemann-Franz law and density-dependent variation of the effective Lorenz number over six orders of magnitude. We find that the transport properties of ultra-clean graphene are quantitatively consistent with that of a hydrodynamic Dirac fluid.