Quantum Hall effect in graphene with twisted bilayer stripe defects

Quantum Hall effect in twisted bilayer graphene.

We address the quantum Hall behavior in twisted bilayer graphene transferred from the C face of SiC. The measured Hall conductivity exhibits the same plateau values as for a commensurate Bernal bilayer. This implies that the eightfold degeneracy of the zero energy mode is topologically protected despite rotational disorder as recently predicted. In addition, an anomaly appears. The densities at...

Electronic properties of twisted bilayer nanoribbons

We study the band structure, density of states, and spatial localization of edge states in twisted bilayer graphene nanoribbons. We devise these ribbons by cutting a stripe of commensurate twisted bilayer graphene along a direction with a maximum number of zigzag edge atoms. Due to the spatially inhomogeneous interlayer coupling, edge states stemming from regions with AB stacking are closer to ...

Broken-Symmetry Quantum Hall States in Twisted Bilayer Graphene

Twisted bilayer graphene offers a unique bilayer two-dimensional-electron system where the layer separation is only in sub-nanometer scale. Unlike Bernal-stacked bilayer, the layer degree of freedom is disentangled from spin and valley, providing eight-fold degeneracy in the low energy states. We have investigated broken-symmetry quantum Hall (QH) states and their transitions due to the interpl...

Quantum Hall effect, screening, and layer-polarized insulating states in twisted bilayer graphene.

We investigate electronic transport in dual-gated twisted-bilayer graphene. Despite the subnanometer proximity between the layers, we identify independent contributions to the magnetoresistance from the graphene Landau level spectrum of each layer. We demonstrate that the filling factor of each layer can be independently controlled via the dual gates, which we use to induce Landau level crossin...

Unconventional quantum Hall effect and Berry’s phase of 2 in bilayer graphene