Mixing of surface and bulk electronic states at a graphite-hexagonal boron nitride interface

TL;DR

This study demonstrates how the electronic states at the interface of graphite and hexagonal boron nitride can be engineered using moiré superlattices, revealing complex phenomena like Lifshitz transitions and Hofstadter's butterfly in three-dimensional materials.

Contribution

It introduces the concept of tuning 3D electronic states via superlattice potentials at interfaces, extending 2D twistronics to three-dimensional crystals.

Findings

Observation of Lifshitz transitions and Brown-Zak oscillations at the interface.

Detection of Hofstadter's butterfly states extending into graphite's bulk.

Control of 3D spectra through interface engineering.

Abstract

Van der Waals assembly enables exquisite design of electronic states in two-dimensional (2D) materials, often by superimposing a long-wavelength periodic potential on a crystal lattice using moir\'e superlattices. Here we show that electronic states in three-dimensional (3D) crystals such as graphite can also be tuned by the superlattice potential arising at the interface with another crystal, namely, crystallographically aligned hexagonal boron nitride. Such alignment is found to result in a multitude of Lifshitz transitions and Brown-Zak oscillations for near-surface 2D states whereas, in high magnetic fields, fractal states of Hofstadter's butterfly extend deep into graphite's bulk. Our work shows a venue to control 3D spectra by using the approach of 2D twistronics.