Electron transmission through a periodically driven graphene magnetic barrier

TL;DR

This paper investigates how a time-harmonic scalar potential affects electron transmission through graphene magnetic barriers, revealing tunable Fano resonances and suppression of Fabry-Perot oscillations, with implications for identifying quasi-bound states.

Contribution

It introduces a non-perturbative Floquet approach to analyze electron transmission in graphene magnetic barriers with oscillating potentials, uncovering novel Fano resonances and transmission behaviors.

Findings

Time-dependent scalar potential suppresses Fabry-Perot oscillations.

Two types of asymmetric Fano resonances are identified.

Oscillating field enhances transmission and allows tuning of Fano line shapes.

Abstract

The kinetic transport of electrons through graphene magnetic barriers is studied theoretically in presence of an external time harmonic scalar potential. The transmission coefficients are calculated in the framework of the non-perturbative Floquet theory using transfer matrix method. The time dependent scalar potential is found to suppress the usual Fabry-Perot oscillations occurring in the transmission through a constant vector potential barrier (corresponding to two oppositely directed delta-function magnetic barriers). Two types of asymmetric Fano resonances (FR) are noted and are discussed for the narrow barrier structure. One of them arises due to the oscillatory mode while the other due to the evanescent mode of the electron wave inside the barrier. In contrast, the oscillating field favors the transmission for rectangular magnetic barrier structure and also exhibits the FR due to the presence of bound state inside the barrier. The characteristic Fano line shape can be tuned by varying the amplitude of the oscillating potential. The detection of such FR offers an efficient tool for the identification of the quasi-bound and evanescent extended states inside the barrier not reported in the literature so far, for the case of graphene magnetic barrier structures.