Transport evidence of superlattice Dirac cones in graphene monolayer on twisted boron nitride substrate

TL;DR

This study demonstrates the creation of superlattice Dirac cones in graphene monolayers on twisted boron nitride substrates, revealing multiple Dirac points and tunable electronic properties, advancing the field of twistronics.

Contribution

It introduces a novel approach of using twisted substrate materials to engineer band structures in 2D materials, expanding the scope of moiré superlattice applications.

Findings

Observation of three pairs of superlattice Dirac points in graphene on twisted BN

Tunable Fermi velocities and gapless dispersion of Dirac cones

Support from band structure calculations confirming experimental results

Abstract

Strong band engineering in two-dimensional (2D) materials can be achieved by introducing moir\'e superlattices, leading to the emergence of various novel quantum phases with promising potential for future applications. Presented works to create moir\'e patterns have been focused on a twist embedded inside channel materials or between channel and substrate. However, the effects of a twist inside the substrate materials on the unaligned channel materials are much less explored. In this work, we report the realization of superlattice multi-Dirac cones with the coexistence of the main Dirac cone in a monolayer graphene (MLG) on a ~0.14{\deg} twisted double-layer boron nitride (tBN) substrate. Transport measurements reveal the emergence of three pairs of superlattice Dirac points around the pristine Dirac cone, featuring multiple metallic or insulating states surrounding the charge neutrality point (CNP). Displacement field tunable and electron-hole asymmetric Fermi velocities are indicated from temperature dependent measurements, along with the gapless dispersion of superlattice Dirac cones. The experimental observation of multiple Dirac cones in MLG/tBN heterostructure is supported by band structure calculations employing periodic moir\'e potential. Our results unveil the potential of using twisted substrate as a universal band engineering technique for 2D materials regardless of lattice matching and crystal orientations, which might pave the way for a new branch of twistronics.