Quantum Hall effect in monolayer-bilayer graphene planar junctions

Abstract

The Hall resistance of a homogeneous electron system is well known to be anti-symmetric with respect to the magnetic field and the sign of charge carriers. We have observed that such symmetries no longer hold in planar hybrid structures consisting of partly single layer graphene (SLG) and partly bilayer graphene (BLG) in the quantum Hall (QH) regime. In particular, the Hall resistance (R 12xy ) across the SLG and BLG interface is observed to exhibit quantized plateaus that switch between those characteristic of SLG QH states and BLG QH states when either the sign of the charge carriers (controlled by a back gate) or the direction of the magnetic field is reversed. Simultaneously reversing both the carrier type and the magnetic field gives rise to the same quantized Hall resistances. The observed SLG-BLG interface QH states, with characteristic asymmetries with respect to the signs of carriers and magnetic field, are determined only by the chirality of the QH edge states and can be explained by a Landauer-Büttiker analysis applied to such graphene hybrid structures involving two regions of different Landau level (LL) structures.

Landau quantization of Dirac fermions in graphene and its multilayers

“…Because the electrons reside at the graphene surface, in contrast to the case of semiconductor-based 2DEGs, it should be possible to directly probe the level bending at the edges and perform systematic studies of the edge states for testing theoretical ideas of quantum Hall edge physics [118]. Numerous works have addressed this subject, mainly using optical and transport measurements [119][120][121]. Direct experimental observation of the LL bending can be achieved by STM and STS at different edge terminations of graphene on the graphite surface [72].…”

Bilayer-induced asymmetric quantum Hall effect in epitaxial graphene

“…[29][30][31] We consider our device as consisting of a monolayer and a bilayer region, both in a QH state, and hosting different numbers of edge states. Differently from the symmetric cases which are found in the literature, 18,20,27 the peculiar asymmetry of the curves in Fig.…”

Supercurrent reversal in Josephson junctions based on bilayer graphene flakes

“…[16][17][18] Moreover in the presence of perpendicular magnetic fields the emergence of Landau levels with peculiar transport properties has been studied. [19][20][21][22] In particular, a rich Landau spectrum has been predicted 19 and an asymmetry in the dependence of transport features to the sign of magnetic field and charge carriers has been experimentally observed. 20 Other theory works have focused on the edge states properties and quantum transport via The length and width of the junction is indicated by d and W , respectively.…”

“…[19][20][21][22] In particular, a rich Landau spectrum has been predicted 19 and an asymmetry in the dependence of transport features to the sign of magnetic field and charge carriers has been experimentally observed. 20 Other theory works have focused on the edge states properties and quantum transport via The length and width of the junction is indicated by d and W , respectively. A voltage difference V0 is applied perpendicularly between the BG layers.…”