Modulation effect on the magneto-electronic and optical properties of graphene

Abstract

The influences of modulated electric fields and modulated magnetic fields on Landau levels (LLs) of monolayer graphene are investigated by the general tight-binding model and gradient approximation Both modulated fields cause the LLs to split into two double-degenerate parabolic subbands; these subbands exhibit periodic oscillations and extra band-edge states However the subband dispersions and oscillation amplitudes that are subjected to electric and magnetic modulated fields behave differently Main features of the electronic structure are reflected in the density of states (DOS) which presents pair-like and square-root divergent structures for both modulated field cases The LL wave functions are strongly affected by both modulated fields the altered features including the broken symmetry displacement of the center location and the varied amplitude strength As to the optical absorption spectra the modulated fields have strong influence on the structure number intensity and frequency of absorption peaks and thus the extra selection rules Each symmetric peak under a uniform magnetic field changes into asymmetric ones with lower intensities The threshold absorption frequency exhibits an obvious evolution in the regard of redshift Moreover the extra peaks in the absorption spectrum might arise from different selection rules For the modulated electric field the extra peaks can relatively easily be identified at higher frequencies and under stronger modulation strength For the modulated magnetic field the extra peaks could be obtained at lower frequencies and under a strong enough modulation strength

Date of Award	2014 Jan 16
Original language	English
Supervisor	Min-Fa Lin (Supervisor)