Analysis of Doorway States in a Graphene Structure

Abstract

Doorway states (DWSs) are related to the strength function phenomenon and giant resonances; and arise when two systems interact: one with a high‐density eigenvalue spectrum and the other with a comparatively lower density. They are important because they constitute a very efficient mechanism for energy absorption when a system has such a state. These concepts, studied first in nuclear physics in the 1940s, are analyzed here from a theoretical point of view in some particular graphene structures, obtained after applying appropriate voltages to a graphene sheet. The influence of the DWSs on the electronic transport in these systems is also studied. To analyze these effects, a graphene sheet is considered to which three electrodes are applied to produce two potential barriers separated by a well. It is shown that, for the thin barrier, the transmission coefficient as a function of the energy has well‐localized maxima, each maximum occurring at the DWS energies. This transmission clearly shows the strength function phenomenon. This function is an envelope for the resonances of the composite system. The results suggest the possibility of building graphene electronic devices, such as filters matching the DWSs.