Quantum interference in a macroscopic van der Waals conductor

TL;DR

This paper reports the discovery of quantum interference-induced magnetoconductance oscillations in macroscopic graphite samples, explained by moiré superlattices, revealing quantum effects over centimeter scales when certain length scales are comparable.

Contribution

It demonstrates that quantum interference effects can be observed in large-scale layered conductors due to moiré superlattices when specific length scales align.

Findings

Magnetoconductance oscillations of order e^2/h observed in macroscopic graphite samples.

Oscillations occur when carriers are confined to lowest Landau levels.

Quantum corrections detectable over centimeter scales under certain conditions.

Abstract

Quantum corrections to charge transport can give rise to an oscillatory magnetoconductance, typically observed in mesoscopic samples with a length shorter than or comparable with the phase coherence length. Here, we report the observation of magnetoconductance oscillations periodic in magnetic field with an amplitude of the order of $e^2/h$ in macroscopic samples of Highly Oriented Pyrolytic Graphite (HOPG). The observed effect emerges when all carriers are confined to their lowest Landau levels. We argue that this quantum interference phenomenon can be explained by invoking moir\'e superlattices with a discrete distribution in periodicity. According to our results, when the magnetic length $\ell_B$, the Fermi wave length $\lambda_F$ and the length scale of fluctuations in local chemical potential are comparable in a layered conductor, quantum corrections can be detected over centimetric length scales.