Microscopic origin of doubled antidot gate periodicity

Determine the microscopic origin of the crossover from the minimal-excitation period to a doubled antidot-gate period in bilayer graphene quantum Hall antidots, distinguishing between quasiparticle bunching and a transition toward an Aharonov–Bohm-dominated or mixed transport regime.

Background

The paper reports a crossover from gate-voltage periodicities corresponding to the minimal quasiparticle charge—$e/4$ for the even-denominator states and $e/3$ for the $=2/3$ state—to approximately twice those periods when the coupling between antidot-bound states and extended edge states is increased through side-gate tuning.

Two interpretations are considered: the localized antidot charge may change through bunching of two minimal quasiparticles, or the device may move from a Coulomb-dominated regime toward an Aharonov–Bohm-dominated or mixed regime in which the gate period is not directly determined by quasiparticle charge. The magnetic-field periodicities, especially the anomalous behavior at $=-1/2$, are not consistently explained by either simple picture. Because side gates simultaneously modify tunnel coupling, electrostatics, confinement, and potentially the reconstructed multimode edge structure, the microscopic mechanism remains unresolved.