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

@article{Kou2014ElectronholeAI, title={Electron-hole asymmetric integer and fractional quantum Hall effect in bilayer graphene}, author={Angela Kou and Benjamin E. Feldman and Andrei J Levin and Bertrand I. Halperin and K. Watanabe and Takashi Taniguchi and Amir Yacoby}, journal={Science}, year={2014}, volume={345}, pages={55 - 57} }

Breaking down graphene degeneracy Bilayer graphene has two layers of hexagonally arranged carbon atoms stacked on top of each other in a staggered configuration. This spatial arrangement results in degenerate electronic states: distinct states that have the same energy. Interaction between electrons can cause the states to separate in energy, and so can external fields (see the Perspective by LeRoy and Yankowitz). Kou et al., Lee et al., and Maher et al. used three distinct experimental setups…

## 86 Citations

### Tunable fractional quantum Hall phases in bilayer graphene

- PhysicsScience
- 2014

Fractional QHE states in BLG that show phase transitions that can be tuned by a transverse electric field are reported, providing a model platform with which to study the role of symmetry-breaking in emergent states with topological order.

### Tunable quantum Hall edge conduction in bilayer graphene through spin-orbit interaction

- PhysicsPhysical Review B
- 2018

Bilayer graphene, in the presence of a one-sided spin-orbit interaction (SOI) induced by a suitably chosen substrate, is predicted to exhibit unconventional Quantum Hall states. The new states arise…

### Broken-Symmetry Quantum Hall States in Twisted Bilayer Graphene

- PhysicsScientific reports
- 2016

This work investigates broken-symmetry quantum Hall (QH) states and their transitions due to the interplay of the relative strength of valley, spin and layer polarizations in twisted bilayer graphene and suggests that the QH states with broken valley and spin symmetries for individual layer become hybridized via interlayer tunnelling.

### Emergent complex states in bilayer graphene

- PhysicsScience
- 2014

A trio of studies in this issue have elucidated the nature of these exotic broken-symmetry states in graphene, making it an even richer system for complex electronic states to emerge.

### Fractional Quantum Hall States in Bilayer Graphene Probed by Transconductance Fluctuations.

- PhysicsNano letters
- 2015

The observed stability of both odd and even denominator fractional QH states is very sensitive to local transverse electric fields in bilayer graphene, and the particle-hole symmetric state at filling 1/2 is detected.

### Composite fermions and broken symmetries in graphene.

- PhysicsNature communications
- 2015

In the first two Landau levels, the two-flux composite-fermion sequences of FQH states between each integer filling factor suggest a broken-valley symmetry, consistent with the observation of a gap at charge neutrality and zero field.

### Landau quantization of Dirac fermions in graphene and its multilayers

- Physics
- 2017

When electrons are confined in a two-dimensional (2D) system, typical quantum–mechanical phenomena such as Landau quantization can be detected. Graphene systems, including the single atomic layer and…

### Even-denominator fractional quantum Hall states in bilayer graphene

- PhysicsScience
- 2017

Transport measurements in dual-gated bilayer graphene suggest that BLG is a platform in which topological ground states with possible non-abelian excitations can be manipulated and controlled.

### Topological approach to quantum Hall effects and its important applications: higher Landau levels, graphene and its bilayer

- Physics
- 2017

Abstract
In this paper the topological approach to quantum Hall effects is carefully described. Commensurability conditions together with proposed generators of a system braid group are employed to…

### Experimental observation of surface states and Landau levels bending in bilayer graphene

- Physics
- 2016

We report on microscopic measurements of the low-energy electronic structures both at the zigzag and armchair edges of bilayer graphene using scanning tunneling microscopy and spectroscopy (STM and…

## References

SHOWING 1-10 OF 60 REFERENCES

### Broken-Symmetry States in Doubly Gated Suspended Bilayer Graphene

- PhysicsScience
- 2010

The underlying order of the various broken-symmetry states in bilayer graphene suspended between top and bottom gate electrodes was investigated and the order parameter was deduced by controllably breaking the spin and sublattice symmetries.

### Fractional quantum Hall phase transitions and four-flux states in graphene.

- PhysicsPhysical review letters
- 2013

Local electronic compressibility measurements of ultraclean suspended graphene reveal a multitude of fractional quantum Hall states surrounding filling factors ν=-1/2 and -1/4, and several of these states exhibit phase transitions that indicate abrupt changes in the underlying order.

### Transport spectroscopy of symmetry-broken insulating states in bilayer graphene.

- PhysicsNature nanotechnology
- 2012

Transport measurements in ultraclean double-gated bilayer graphene are reported and source-drain bias is used as a spectroscopic tool to resolve a gap of ∼2 meV at the charge neutrality point, which represents the firstSpectroscopic mapping of the ground states in bilayers graphene in the presence of both electric and magnetic fields.

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

- Physics
- 2006

There are two known distinct types of the integer quantum Hall effect. One is the conventional quantum Hall effect, characteristic of two-dimensional semiconductor systems1,2, and the other is its…

### Massive Dirac Fermions and Hofstadter Butterfly in a van der Waals Heterostructure

- PhysicsScience
- 2013

Band structure engineering in a van der Waals heterostructure composed of a monolayer graphene flake coupled to a rotationally aligned hexagonal boron nitride substrate is demonstrated, resulting in an unexpectedly large band gap at charge neutrality.

### Unconventional Sequence of Fractional Quantum Hall States in Suspended Graphene

- PhysicsScience
- 2012

Graphene provides a rich platform to study many-body effects, owing to its massless chiral charge carriers and the fourfold degeneracy arising from their spin and valley degrees of freedom, and an unusual pattern of incompressible fractional quantum Hall states that follows the standard composite fermion sequence between filling factors but involves only even-numerator fractions between ν = 1 and 2.

### Tunable electron interactions and fractional quantum Hall States in graphene.

- PhysicsPhysical review letters
- 2011

A method to continuously tune the effective electron interactions in graphene and its bilayer by the dielectric environment of the sample to realize and stabilize various strongly correlated phases and explore the transitions between them is proposed.

### Observation of even denominator fractional quantum Hall effect in suspended bilayer graphene.

- PhysicsNano letters
- 2014

Low-temperature magneto-transport in recently developed, high-quality multiterminal suspended bilayer graphene devices, enabling the independent measurement of the longitudinal and transverse resistance, offers new possibilities to explore the microscopic nature of even-denominator fractional quantum Hall effect.

### Particle-hole symmetry and bifurcating ground-state manifold in the quantum Hall ferromagnetic states of multilayer graphene

- Physics
- 2013

The orbital structure of the quantum Hall ferromagnetic states in the zero-energy Landau level in chiral multilayer graphene (AB, ABC, ABCA, etc. stackings) is determined by the exchange interaction…

### Landau-level degeneracy and quantum Hall effect in a graphite bilayer.

- PhysicsPhysical review letters
- 2006

We derive an effective two-dimensional Hamiltonian to describe the low-energy electronic excitations of a graphite bilayer, which correspond to chiral quasiparticles with a parabolic dispersion…