The Effect of Twisting Angle on the Electronic Properties and Electron Transport and Hall Effect in the Twisted Circular and Rectangular Graphene and Graphene/Boron-Nitride Channels

TL;DR

This study investigates how twisting angles affect the electronic properties, electron transport, and Hall effect in various graphene nanoribbons and heterostructures, revealing angle-dependent phase transitions and quantum phenomena relevant for nanochannel applications.

Contribution

It provides a detailed analysis of electronic behavior in twisted graphene nanoribbons and heterostructures, highlighting the impact of twist angles on phase transitions and transport mechanisms.

Findings

Circular tGNs exhibit metallic behavior at all twist angles.

Rectangular tGNs undergo metal-to-semiconductor transition with increasing twist angle.

Hall conductivity shows quantized Landau levels in circular tGNs and complex behavior in rectangular ones.

Abstract

Twisted bilayer graphene (tBLG) including interlayer interaction and rotational disorder shows anomalous electron transport as a function of twist-angles (tAs). In this work, we address the electronic properties and electron transport of circular and rectangular twisted graphene nanoribbon (tGN) and twisted heterostructure of graphene/boron-nitride nanoribbon (thG/BNN) channels by applying the tight-binding Hamiltonian for two regimes of small and large tAs. Analysis of band structure reveals that the circular tGNs for small and large tAs have metallic behavior, while phase transition of metal to semiconductor occurs in rectangular case, sweeping small tAs to large ones. This implies a different transport mechanism depending on the tAs disorder, whiles the Klein paradox appears in the transmission and conductance of circular tGNs. We distinguish that the local electron states of rectangular tGNs with large tAs create degenerate multiflat bands, supporting decoupling of two ribbons and high conductance state. However, coupled two Dirac electron gases for small tAs of rectangular channel cause Klein paradox due to their resonant scattering. We compute the Hall conductivity in both tGNs for wide range of magnetic field. In circular tGNs the valance and conduction band energy is quantized into electron/hole-like Landau level, while for rectangular tGNs with applied magnetic field the Hall conductivity shows complex behavior. Moreover, we provide a platform for quantum transport and Hall effect of thG/BNN, which host a vast nontrivial emergent electronic state. Our findings suggest that circular/rectangular tGNs and thG/BNNs with new electron states of Moir\'e pattern besides the Klein paradox suitable for switching of several nanochannel.