2023/11/10 by Priyanka Sinha, Ayan Mondal, Sinha, Priyanka +5
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Graphene research and applications #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Quantum and electron transport phenomena #Strongly Correlated Electrons (cond-mat.str-el) #Surface and Thin Film Phenomena
paper · pdf · doi:10.48550/arxiv.2311.06215
openalex publication_date 2023/11/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We extensively investigate the electronic and transport properties of a twisted bilayer graphene when subjected to both an external perpendicular electric field and a magnetic field. Using a basic tight-binding model, we show the flat electronic band properties as well as the density of states (DOS), both without and with the applied electric field. In the presence of an electric field, the degeneracy at the Dirac points is lifted where the non-monotonic behavior of the energy gap exists, especially for twist angles below 3^∘. We also study the behavior of the Landau levels (LL) spectra for different twist angles within a very low energy range. These LL spectra get modified under the influence of the external electric field. Moreover, we calculate the dc Hall conductivity (σxy) for a very large system using the Kernel Polynomial Method (KPM). Interestingly, σxy makes a transition from a half-integer to an integer quantum Hall effect, i.e. the value of σxy shifts from ± 4(n+1/2) (2e2/h) (n is an integer) to ± 2n (2e2/h) around a small twist angle of θ=2.005^∘. At this angle, σxy acquires a Hall plateau at zero Fermi energy. However, the behavior of σxy remains unaltered when the system is exposed to the electric field, particularly at the magic angle where the bands in both layers can hybridize and strong interlayer coupling plays a crucial role.