Shift-current response as a probe of quantum geometry and electron-electron interactions in twisted bilayer graphene

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...

Quantum chaotic tunneling in graphene systems with electron-electron interactions

Lei Ying,1 Guanglei Wang,1 Liang Huang,1,2 and Ying-Cheng Lai1,3,* 1School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA 2Institute of Computational Physics and Complex Systems, and Key Laboratory for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou, Gansu 730000, China 3Department of Physics, Arizona State University, T...

Bilayer graphene. Electron-hole asymmetric integer and fractional quantum Hall effect in bilayer graphene.

The nature of fractional quantum Hall (FQH) states is determined by the interplay between the Coulomb interaction and the symmetries of the system. The distinct combination of spin, valley, and orbital degeneracies in bilayer graphene is predicted to produce an unusual and tunable sequence of FQH states. Here, we present local electronic compressibility measurements of the FQH effect in the low...

A Probe of Electron Interactions in Coupled Quantum Wells

Electron-electron interactions in graphene bilayers

We study the effect of electron-electron interactions in the quasiparticle dispersion of a graphene bilayer within the Hartree-Fock-Thomas-Fermi theory by using a four-bands model. We find that the electronic fluid can be described by a non-interacting like dispersion but with renormalized parameters. We compare our results with recent cyclotron resonance experiments in this system. Since graph...