Direct observation of magneto-electric Aharonov-Bohm effect in moir\'e-scale quantum paths of minimally twisted bilayer graphene

TL;DR

This study demonstrates the use of scanning tunneling microscopy as a nanometer-scale Aharonov-Bohm interferometer to directly observe magneto-electric AB effects in minimally twisted bilayer graphene, revealing quantum interference along moiré-scale paths.

Contribution

It introduces a novel STM-based method to directly measure magnetic and electrostatic AB oscillations at the nanoscale in twisted bilayer graphene.

Findings

Direct measurement of AB oscillations in TBG using STM.

Identification of chiral 1D states at domain boundaries.

Observation of electron interference along moiré-scale paths.

Abstract

Aharonov-Bohm (AB) effect, the well-known archetype of electron-wave interference phenomena, has been explored extensively through transport measurements. However, these techniques lack spatial resolution that would be indispensable for studying the magnetic and electrostatic AB oscillations at the nanometer scale. Here, we demonstrated that scanning tunneling microscopy (STM) can be used as an AB interferometer operating on nanometer length scales and the magneto-electric Aharonov-Bohm effect in minimally twisted bilayer graphene (TBG) was directly measured by using STM. In the minimally TBG, there is a triangular network of chiral one-dimensional states hosted by domain boundaries due to structural reconstruction. Taking advantage of the high spatial resolution of the STM, both the magnetic and electrostatic AB oscillations arising from electron interference along moir\'e-scale triangular quantum paths in the minimally TBG were measured. Our work enables measure and control of the AB effect and other electron-wave interference at the nanoscale.