Edge channels of broken-symmetry quantum Hall states in graphene visualized by atomic force microscopy

  title={Edge channels of broken-symmetry quantum Hall states in graphene visualized by atomic force microscopy},
  author={Sungmin Kim and Johannes Schwenk and Daniel Walkup and Yihang Zeng and Fereshte Ghahari and Son T. Le and Marlou R. Slot and Julian Berwanger and Steve Blankenship and Kenji Watanabe and Takashi Taniguchi and Franz J. Giessibl and Nikolai B. Zhitenev and Cory R. Dean and Joseph A. Stroscio},
  journal={Nature Communications},
The quantum Hall (QH) effect, a topologically non-trivial quantum phase, expanded the concept of topological order in physics bringing into focus the intimate relation between the “bulk” topology and the edge states. The QH effect in graphene is distinguished by its four-fold degenerate zero energy Landau level (zLL), where the symmetry is broken by electron interactions on top of lattice-scale potentials. However, the broken-symmetry edge states have eluded spatial measurements. In this… 
9 Citations
Imaging field-tuned quantum Hall broken-symmetry orders and quantum Hall conducting channel in charge-neutral graphene WSe2 heterostructure
The zeroth Landau level (0LL) in graphene has emerged as a flat-band platform in which distinct many-body phases can be explored with unprecedented control by simply tuning the strength and/or
Visualizing broken symmetry and topological defects in a quantum Hall ferromagnet
Visualizing atomic-scale electronic wave functions with scanning tunneling spectroscopy (STS) and resolving microscopic signatures of valley ordering in QHFM phases and spectral features of fractional quantum Hall phases of graphene observed observed a field-tuned continuous quantum phase transition from a valley-polarized state to an intervalley coherent state.
Theory of competing charge density wave, Kekulé, and antiferromagnetically ordered fractional quantum Hall states in graphene aligned with boron nitride
We investigate spin and valley symmetry-broken fractional quantum Hall phases within a formalism that naturally extends the paradigm of quantum Hall ferromagnetism from integer to fractional quantum
Electrically switchable tunneling across a graphene pn junction: evidence for canted antiferromagnetic phase in $\nu=0$ state
The ground state of a graphene sheet at charge neutrality in a perpendicular magnetic field remains enigmatic, with various experiments supporting canted antiferromagnetic, bond ordered, and even
Coupling confined states in nanoporous molecular networks to an atomic force microscope
Periodic confinement of surface electrons in atomic structures or extended nanoporous molecular networks is the archetype of a two-dimensional quantum dot (QD) superlattice. Yet, an electrical control
Contacts and upstream modes explain the electron-hole asymmetry in the graphene quantum Hall regime
N. Moreau, B. Brun, S. Somanchi, K. Watanabe, T. Taniguchi, C. Stampfer & B. Hackens 1 IMCN/NAPS, Université catholique de Louvain (UCLouvain), B-1348 Louvain-la-Neuve, Belgium 2 JARA-FIT and 2nd
Spin waves in doped graphene: A time-dependent spin density functional approach to collective excitations in paramagnetic two-dimensional Dirac fermion gases
In spin-polarized itinerant electron systems, collective spin-wave modes arise from dynamical exchange and correlation (xc) effects. We here consider spin waves in doped paramagnetic graphene with


Quantum Hall Effect in a Gate-Controlled p-n Junction of Graphene
The realization of a single-layer graphene p-n junction is reported in which carrier type and density in two adjacent regions are locally controlled by electrostatic gating, consistent with recent theory.
Even-denominator fractional quantum Hall states at an isospin transition in monolayer graphene
In monolayer graphene, the two inequivalent sublattices of carbon atoms combine with the electron spin to give electrons a nearly fourfold degenerate internal isospin. At high magnetic fields, the
Tunable symmetry breaking and helical edge transport in a graphene quantum spin Hall state
Graphene has a quantum spin Hall state when it is subjected to a very large magnetic field angled with respect to the graphene plane, which constitutes a new kind of one-dimensional electronic system with a tunable bandgap and an associated spin texture.
Experimental observation of the quantum Hall effect and Berry's phase in graphene
An experimental investigation of magneto-transport in a high-mobility single layer of graphene observes an unusual half-integer quantum Hall effect for both electron and hole carriers in graphene.
Flavour Hund's coupling, Chern gaps and charge diffusivity in moiré graphene.
This work investigates the broken-symmetry many-body ground state of magic-angle twisted bilayer graphene (MATBG) and its nontrivial topology using simultaneous thermodynamic and transport measurements and directly observes flavour symmetry breaking as pinning of the chemical potential at all integer fillings of the moiré superlattice.
Interaction-driven quantum Hall wedding cake–like structures in graphene quantum dots
The development of a “wedding cake”–like structure of concentric regions of compressible-incompressible quantum Hall states, a signature of electron interactions in the system are directly observed.
Nanoscale imaging of equilibrium quantum Hall edge currents and of the magnetic monopole response in graphene
Although the recently predicted topological magnetoelectric effect 1 and the response to an electric charge that mimics an induced mirror magnetic monopole 2 are fundamental attributes of topological
Unconventional quantum Hall effect and Berry’s phase of 2π in bilayer graphene
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
Correlated insulator behaviour at half-filling in magic-angle graphene superlattices
It is shown experimentally that when this angle is close to the ‘magic’ angle the electronic band structure near zero Fermi energy becomes flat, owing to strong interlayer coupling, and these flat bands exhibit insulating states at half-filling, which are not expected in the absence of correlations between electrons.
High-Quality Electrostatically Defined Hall Bars in Monolayer Graphene.
The working principle of a new generation of high-quality gate-defined graphene samples is demonstrated, where the challenge of doing so in a gapless semiconductor is overcome by using the ν = 0 insulating state, which emerges at modest applied magnetic fields.