Quantum Hall interferometry in triangular domains of marginally twisted bilayer graphene

TL;DR

This paper introduces a novel quantum Hall interferometer using marginally twisted bilayer graphene, demonstrating phase-coherent interference of edge modes in a simple device structure, advancing the study of non-Abelian braiding statistics.

Contribution

It presents the first demonstration of quantum Hall interference effects intrinsic to triangular domains in twisted bilayer graphene without complex gating.

Findings

Observation of Fabry-Pérot and Aharonov-Bohm oscillations in magneto-thermopower.

Interference effects are intrinsic to triangular AB/BA domains, reducing Coulomb charging.

Phase coherence achieved without additional gate-defined structures.

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 $\theta$ $\approx$ $0.16$ $^{\circ}$. With the device operating in the QH regime, we observe distinct signatures of electronic Fabry-P\'{e}rot (FP) and Aharonov-Bohm (AhB)-oscillations of the magneto-thermopower in the density-magnetic field phase-space, at Landau level filling factors $\nu=4$,$8$. 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.