Band Structure Engineering of 2D Materials using Patterned Dielectric Superlattices

TL;DR

This paper presents a novel method for engineering the electronic band structure of 2D materials using patterned dielectric superlattices, enabling precise control over electronic properties and the observation of complex quantum phenomena.

Contribution

The authors introduce a new fabrication approach combining surface dielectric patterning with van der Waals materials, allowing high mobility superlattice devices with smaller wavelength patterns and dynamic tunability.

Findings

Demonstrated replica Dirac cones with sub 40nm superlattice patterns in graphene.

Observed Hofstadter spectra under large magnetic fields with designed lattice symmetries.

Achieved improved electrostatics enabling finer superlattice patterning.

Abstract

The ability to manipulate two-dimensional (2D) electrons with external electric fields provides a route to synthetic band engineering. By imposing artificially designed and spatially periodic superlattice (SL) potentials, 2D electronic properties can be further engineered beyond the constraints of naturally occurring atomic crystals. Here we report a new approach to fabricate high mobility SL devices by integrating surface dielectric patterning with atomically thin van der Waals materials. By separating the device assembly and SL fabrication processes, we address the intractable tradeoff between device processing and mobility degradation that constrains SL engineering in conventional systems. The improved electrostatics of atomically thin materials moreover allows smaller wavelength SL patterns than previously achieved. Replica Dirac cones in ballistic graphene devices with sub 40nm wavelength SLs are demonstrated, while under large magnetic fields we report the fractal Hofstadter spectra from SLs with designed lattice symmetries vastly different from that of the host crystal. Our results establish a robust and versatile technique for band structure engineering of graphene and related van der Waals materials with dynamic tunability.