Thermodynamic Imaging Reveals the Nature of Out-of-Equilibrium Transport in Moiré Graphene - Part I

Recent experiments on nonlinear transport in graphene/hBN moiré system have observed striking transport characteristics. At high bias, sharp gate-tunable differential resistance peaks were observed. Similar phenomenology has been seen in twisted bilayer graphene near and at the magic angle. These tunable resistance peaks were associated with the Schwinger mechanism of electron-hole pair creation. However, to date, these observations are based only on transport measurements, which probe only integrated behavior, and cannot reveal the microscopic structure along the bulk of the sample.

Part I of this talk will focus on equilibrium thermodynamic measurements of the graphene/hBN moiré system, using a scanning nanotube Single Electron Transistor (SET). These measurements reveal the energy bands of Gr/hBN moiré with an unprecedented level of detail. Based on these energy bands, we unambiguously conclude that the tunable resistive peaks are not associated with the Schwinger mechanism.