Fig. 1: Device characterization and ν = 1 sensitivity to magnons.
a, Schematic of the experimental setup. The red and blue arrows denote the hot and cold quantum Hall edge states, respectively. The green curve denotes magnon generation for µ > EZ. b, Optical micrograph of the hBN-encapsulated monolayer graphene device. Scale bar, 2 µm. TG denotes the top gate. The white arrows indicate the chirality of the quantum Hall edge states. c, Two-terminal conductance G2T near the ν = 1 plateau measured at 11 T between contacts 2 and 3 with zero volts applied to the top gate. The plateau breaks down principally around ±EZ. d, The µ(ν) measured at 11 T in the bulk near contact 5 at Vd.c. = 0 and 10 mV. The gap, taken as the peak excursion, is reduced in the case of Vd.c. = 10 mV. e, Bias-dependent energy gap extracted from the chemical potential measurements as in d. The gap begins to reduce near ±EZ marked by the grey dotted lines.
