Tunneling conductance through gapped bilayer graphene junctions

TL;DR

This paper investigates the tunneling conductance in gapped bilayer graphene junctions, revealing how band gap, bias voltage, and stacking order influence conductance features such as anti-resonances, energy gaps, and Klein tunneling.

Contribution

It provides a detailed analysis of conductance behavior in gapped bilayer graphene junctions considering different stacking orders and bias conditions, highlighting new anti-resonance and tunneling phenomena.

Findings

Conductance shows anti-resonances with the same period in certain configurations.

Gapped AB-BLG creates a global energy gap affecting conductance.

Presence of Klein and anti-Klein tunneling depending on the junction setup.

Abstract

The conductance through single-layer graphene (SLG) and AA/AB-stacked bilayer graphene (BLG) junctions is obtained by taking into account band gap and bias voltage terms. First, we consider gapped SLG, while in between, they are connected into pristine BLG. For Fermi energy larger than the interlayer hopping, the conductance as a function of the bilayer region length $d$ reveals two different models of anti-resonances with the same period. As a function of the band gap, with AA-BLG stacking, the results show that the conductance has the same minima whatever the value of $d$, and for AB-BLG, $d$ remains relevant such that the system creates a global energy gap. Second, we consider pristine SLG, and in between, they are connected to gapped-biased BLG. We observe the appearance of peaks in the conductance profile with different periods and shapes, and also the presence of Klein tunneling with zero conductance in contrast to the first configuration. When $ d $ is less than 10, $G(E)$ vanishes and exhibits anti-Klein tunneling as a function of the Fermi energy $E$. We also investigate the conductance as a function of the bias. For AA-BLG, the results show antiresonances and diminish for a large value of the bias, independently of the bilayer region of length. In contrast, the conductance in AB-BLG has distinct characteristics in that it begins conducting with maxima for small $E$ and with minima for large $E$.