Transport properties of bilayer graphene in a strong in-plane magnetic field

TL;DR

This paper investigates how a strong in-plane magnetic field alters the electronic transport in bilayer graphene, revealing a transition to monolayer-like behavior and changes in tunneling and conductance properties depending on field orientation.

Contribution

It demonstrates how in-plane magnetic fields induce a transition from bilayer to monolayer-like electronic behavior in graphene, affecting transmission and conductance in orientation-dependent ways.

Findings

Magnetic field causes bilayer to split into two Dirac cones, altering transport.

Orientation of magnetic field influences tunneling and conductance, with enhancement or suppression.

Transmission resonances shift and transform with increasing magnetic field.

Abstract

A strong in-plane magnetic field drastically alters the low-energy spectrum of bilayer graphene by separating the parabolic energy dispersion into two linear Dirac cones. The effect of this dramatic change on the transport properties strongly depends on the orientation of the in-plane magnetic field with respect to the propagation direction of the charge carriers and the angle at which they impinge on the electrostatic potentials. For magnetic fields oriented parallel to the potential boundaries an additional propagating mode that results from the splitting into Dirac cones enhances the transmission probability for charge carriers tunneling through the potentials and increases the corresponding conductance. Our results show that the chiral suppression of transmission at normal incidence is turned into a chiral enhancement when the magnetic field increases, thus indicating a transition from a bilayer to a monolayer-like system at normal incidence. Further, we find that the typical transmission resonances stemming from confinement in a potential barrier are shifted to higher energy and are eventually transformed into anti-resonances with increasing magnetic field. For magnetic fields oriented perpendicular to the potential boundaries we find a very pronounced transition from a bilayer system to two separated monolayer-like systems with Klein tunneling emerging at certain incident angles symmetric around 0, which also leaves a signature in the conductance. For both orientations of the magnetic field, the transmission probability is still correctly described by pseudospin conservation. Finally, to motivate the large in-plane magnetic field, we show that its energy spectrum can be mimicked by specific lattice deformations such as a relative shift of one of the layers. With this equivalence we introduce the notion of an in-plane pseudo-magnetic field.