Minibands in twisted bilayer graphene probed by magnetic focusing

@article{Berdyugin2019MinibandsIT,
  title={Minibands in twisted bilayer graphene probed by magnetic focusing},
  author={Alexey I. Berdyugin and B Tsim and Piranavan Kumaravadivel and S. G. Xu and A. Ceferino and Angelika Knothe and R. Krishna Kumar and Takashi Taniguchi and K. Watanabe and Andre K. Geim and Irina V. Grigorieva and Vladimir I. Fal’ko},
  journal={Science Advances},
  year={2019},
  volume={6}
}
Detection of magnetic focusing peaks allows probing of minibands in the energy spectrum of twisted bilayer graphene. Magnetic fields force ballistic electrons injected from a narrow contact to move along skipping orbits and form caustics. This leads to pronounced resistance peaks at nearby voltage probes as electrons are effectively focused inside them, a phenomenon known as magnetic focusing. This can be used not only for the demonstration of ballistic transport but also to study the… 

Valley splitter and transverse valley focusing in twisted bilayer graphene

We study transport in twisted bilayer graphene and show that electrostatic barriers can act as valley splitters, where electrons from the $K$ ($K'$) valley are transmitted only to e.g.\ the top

Combined Minivalley and Layer Control in Twisted Double Bilayer Graphene.

Control over minivalley polarization and interlayer coupling is demonstrated in double bilayer graphene twisted with an angle of 2.37°, offering new opportunities for realizing valleytronics devices such as valley valves, filters, and logic gates.

Tuning superconductivity in twisted bilayer graphene

This study demonstrates twisted bilayer graphene to be a distinctively tunable platform for exploring correlated states by inducing superconductivity at a twist angle larger than 1.1°—in which correlated phases are otherwise absent—by varying the interlayer spacing with hydrostatic pressure.

CVD-based small-angle twisted bilayer graphene

To realize the applicative potential of 2D materials twistronics, scalable synthesis and assembly techniques need to meet stringent requirements in terms of interface cleanness and twist-angle

Correlated States in Strained Twisted Bilayer Graphenes Away from the Magic Angle

Graphene moiré superlattice formed by rotating two graphene sheets can host strongly correlated and topological states when flat bands form at so-called magic angles. Here, we report that, for a

Moiré-Induced Transport in CVD-Based Small-Angle Twisted Bilayer Graphene

To realize the applicative potential of 2D twistronic devices, scalable synthesis and assembly techniques need to meet stringent requirements in terms of interface cleanness and twist-angle

Out-of-Plane Dielectric Susceptibility of Graphene in Twistronic and Bernal Bilayers

It is shown that monolayers in tBLG are described well by polarizability αexp = 10.8 Å3 and effective out-of-plane dielectric susceptibility ϵz = 2.5, including their on-layer electron density distribution at zero magnetic field and the interlayer Landau level pinning at quantizing magnetic fields.

Fractional focusing peaks and collective dynamics in two-dimensional Fermi liquids

Carrier transport in materials is often diffusive due to momentum-relaxing scattering with phonons and defects. Suppression of momentum-relaxing scattering can lead to the ballistic and hydrodynamic

Cloning of zero modes in one-dimensional graphene superlattices

One-dimensional (1D) graphene superlattices have been predicted to exhibit zero-energy modes a decade ago, but an experimental proof has remained missing. Motivated by a recent experiment that could

Mirror symmetry breaking and lateral stacking shifts in twisted trilayer graphene

We construct a continuum model of twisted trilayer graphene using ab initio density-functionaltheory calculations, and apply it to address twisted trilayer electronic structure. Our model accounts

References

SHOWING 1-10 OF 41 REFERENCES

Tuning superconductivity in twisted bilayer graphene

This study demonstrates twisted bilayer graphene to be a distinctively tunable platform for exploring correlated states by inducing superconductivity at a twist angle larger than 1.1°—in which correlated phases are otherwise absent—by varying the interlayer spacing with hydrostatic pressure.

Transport Through a Network of Topological Channels in Twisted Bilayer Graphene.

This work demonstrates coherent electronic transport in a lattice of topologically protected states in the moiré crystal of minimally twisted bilayer graphene and observes Fabry-Pérot and Aharanov-Bohm oscillations that are robust in magnetic fields, indicating that charge carriers in the bulk flow in topologicallyprotected, one-dimensional channels.

Tunable moiré bands and strong correlations in small-twist-angle bilayer graphene

It is demonstrated that at small twist angles, the electronic properties of bilayer graphene moiré crystals are strongly altered by electron–electron interactions.

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

It is demonstrated that the filling factor of each layer can be independently controlled via the dual gates, which are used to induce Landau level crossings between the layers.

Quantum Hall effect in Bernal stacked and twisted bilayer graphene grown on Cu by chemical vapor deposition

We examine the quantum Hall effect in bilayer graphene grown on Cu substrates by chemical vapor deposition. Spatially resolved Raman spectroscopy suggests a mixture of Bernal (A-B) stacked and

Unconventional superconductivity in magic-angle graphene superlattices

The realization of intrinsic unconventional superconductivity is reported—which cannot be explained by weak electron–phonon interactions—in a two-dimensional superlattice created by stacking two sheets of graphene that are twisted relative to each other by a small angle.

Cloning of Dirac fermions in graphene superlattices

Graphene superlattices such as this one provide a way of studying the rich physics expected in incommensurable quantum systems and illustrate the possibility of controllably modifying the electronic spectra of two-dimensional atomic crystals by varying their crystallographic alignment within van der Waals heterostuctures.

van der Waals Heterostructures with High Accuracy Rotational Alignment.

To illustrate the applicability of this technique to realize vdW heterostructures in which the functionality is critically dependent on rotational alignment, this work demonstrates resonant tunneling double bilayer graphene heterostructure separated by hexagonal boron-nitride dielectric.

High-temperature quantum oscillations caused by recurring Bloch states in graphene superlattices

It is shown that graphene superlattices support a different type of quantum oscillation that does not rely on Landau quantization, and this work hints at unexplored physics in Hofstadter butterfly systems at high temperatures.

Flat bands in slightly twisted bilayer graphene: Tight-binding calculations

The presence of flat bands near Fermi level has been proposed as an explanation for high transition temperature superconductors. The bands of graphite are extremely sensitive to topological defects