Extended Data Fig. 2: Deviation between experimental potential well and parabolic potential well.
From: Giant orbital magnetic moments and paramagnetic shift in artificial relativistic atoms and molecules
a, Experimentally measured dI/dVS (VS, d) for the same QD shown in Fig. 2a at VG = −16 V along a line across the center of a circular graphene pn junction. Colored lines are quadratic potential wells with different κ values. The set point used to acquire the tunneling spectra was I = 1 nA, VS = −200 mV, with a 2 mV ac modulation. b, Schematic of the deviation between experimental potential well and parabolic potential well at more negative energies. The experimental potential well deviates from parabolic potential well at more negative energies, and the actual QD radius will be larger than the parabolic potential well. This explains the faster increase of experimentally measured μ than the theoretical values for graphene QDs with a quadratic potential well.
