Electron transport properties for a zigzag graphene nanoribbon embedding multiple rectangular quantum dots under a periodically modulated magnetic field

Abstract

Based on the tight-binding model and recursive Green-function method, the electronic transport properties for a zigzag graphene nanoribbon (ZGNR) embedded with a finite-length superlattice composing of a single or multiple rectangular quantum dot (s) under a periodically modulated magnetic field are investigated. The numerical results of simulation show that the transmittance coefficient T is not only related to the structure of the finite-length superlattice, but also to the addition of a periodically modulated magnetic field. By increasing the height or width of a single rectangular quantum dot (QD), resonant dip of the transmission coefficient T distinctly shifts toward the lower energy region. For a ZGNR embedding n rectangular QDs, the resonant peak splitting is (n-1)-fold in the most energy regions, while the resonant peak splitting is (n-2)-fold in transmission zero (E ≈ 0.37). Nevertheless, three new resonant peaks appear at E ≈ 0.29, E ≈ 0.61 and E ≈ 0.71 under the addition of a periodically modulated magnetic field. Correspondingly, the resonance peak splitting becomes n-fold in the minigap at the edge of transmittance plateau (high energy side). It is determined that the number of quasibound states in the ZGNR can be controlled under a periodically modulated magnetic field. In addition, the conductance and local density of states (LDOS) of ZGNRs are discussed, respectively. With increasing the width of a single rectangular QD, the conductance gradually decreases in the Fermi energy. An uprush peak of the LDOS appears at the position of the conductance peaks or dips under a magnetic field. Therefore, these interesting quantum phenomena are expected to be used as the building blocks of the future nanoelectronics.