Electronic and pseudomagnetic properties of hybrid carbon/boron-nitride nanomaterials via ab-initio calculations and elasticity theory

Abstract

Low dimensional materials such as Boron Nitride nanotube (BNNT) and graphene are attractive for demonstrating several fundamental physical properties and development of novel technologies in nano/micro-scale devices. Although various 3D carbon-based architectures are reported via covalent connection of carbon allotropes, the introduction of analogous 3D hybrid carbon/BN allotropes and determining their exquisite junction-induced properties remain elusive. Here, we focus on mono- and double-layer hybrid graphene/BNNT and graphene/carbon nanotubes (CNT) architectures and explore their diverse junction configuration-induced electronic and pseudomagnetic properties via ab-initio calculations and elasticity theory. By introducing heptagonal and octagonal rings in the junctions, we find that the mismatch between the defected graphene and the BNNT/CNT diameters creates a bond strain at the junction, thus inducing a gauge field and pseudomagnetic field, which decay exponentially along the radial distance of the junction. Furthermore, our analysis of the band structures and density of states in hybrid double-layer architectures demonstrate that there exists a flat band and band dispersion near the Fermi level of graphene/CNT junctions, a feature not present in the graphene/BNNT junction due to the intrinsic wide band gap of BNNT. Finally, our size-effect study shows that while the band gap energy of heptagonal graphene/CNT junction and octagonal graphene/BNNT junctions is sensitive to the nanotube length, this is not the case for octagonal graphene/CNT junctions due to the less perturbation of the electronic states of the valence bond (VB) in the octagonal graphene/CNT junctions. Together, these findings have important implications on science-based engineering of numerous hybrid carbon and boron nitride allotropes while significantly broadening the spectrum of strategies for fabricating new hybrid nanomaterials through covalent connection of dissimilar low-dimensional materials.