Quantum Hall Interferometry in Triangular Domains of Marginally Twisted Bilayer Graphene

Abstract

Quantum Hall (QH) interferometry provides an archetypal platform for the experimental realization of braiding statistics of fractional QH states. However, the complexity of observing fractional statistics requires phase coherence over the length of the interferometer, as well as suppression of Coulomb charging energy. Here, we demonstrate a new type of QH interferometer based on marginally twisted bilayer graphene (mtBLG), with a twist angle θ ≈ 0.16°. With the device operating in the QH regime, we observe distinct signatures of electronic Fabry−Peŕot and Aharonov−Bohm oscillations of the magneto-thermopower in the density−magnetic field phase space, at Landau level filling factors ν = 4, 8. We find that QH interference effects are intrinsic to the triangular AB/BA domains in mtBLG that show diminished Coulomb charging effects. Our results demonstrate phase-coherent interference of QH edge modes without any additional gate-defined complex architecture, which may be beneficial in experimental realizations of non-Abelian braiding statistics.

Emergent phases in graphene flat bands

“…Band structure reprinted (figure) with permission from [69], Copyright (2017) by the American Physical Society. 0.5 • , where interesting phenomena such as Aharanov Bohm effect and Fabry-Perot oscillations have been observed [82][83][84]. The band structure and DOS for non-relaxed (red dashed line) and relaxed (black solid line) configurations presented in figure 4(d) show two primary differences.…”