Designer gapped and tilted Dirac cones in lateral graphene superlattices

TL;DR

This paper demonstrates how a planar array of bipolar waveguides in graphene can be used to engineer gapped and tilted Dirac cones with tunable properties for terahertz applications, enabling new device functionalities.

Contribution

It introduces a method to create and control gapped and tilted Dirac cones in graphene superlattices using gate voltages, which was not previously achievable.

Findings

Gapped and tilted Dirac cones can be engineered in graphene superlattices.

The tilt and gap of Dirac cones are tunable via gate voltages.

Potential for terahertz device applications through Dirac cone engineering.

Abstract

We show that a planar array of bipolar waveguides in graphene can be used to engineer gapped and tilted two-dimensional Dirac cones within the electronic band structure. The presence of these gapped and tilted Dirac cones is demonstrated through a superlattice tight-binding model and verified using a transfer matrix calculation. By varying the applied gate voltages, the tilt parameter of these Dirac cones can be controlled and their gaps can be tuned to fall in the terahertz range. The possibility of gate-tunable gapped Dirac cones gives rise to terahertz applications via interband transitions and designer Landau level spectra both of which can be controlled via Dirac cone engineering. We anticipate that our paper will encourage Dirac cone tilt and gap engineering for gate-tunable device applications in lateral graphene superlattices.