Near-field photocurrent imaging of graphene in high magnetic field

We present an investigation of the local optical and thermal dynamics in graphene within the quantum Hall regime using advanced near-field optical and photocurrent nanoscopy techniques. Near the charge neutrality point, we observe pronounced optical and photothermal responses that evolve with doping levels. Notably, at higher doping and specific integer filling factors, a reemergence of photothermal signals over large scales suggests intriguing nonlocal thermal effects in the insulating regime. These findings reveal unexpected transport behaviors, providing new insights into the interplay between electronic and thermal properties in two-dimensional electron systems under strong magnetic fields. Our results offer novel insights into nanoscale thermal and electronic transport, magnetoexcitons, and chiral edge states in canonical 2D electron gas systems under the time-reversal symmetry breaking condition.