Bilayer graphene as an helical quantum Hall ferromagnet

Abstract

The two-dimensional electron gas in a bilayer graphene in the Bernal stacking supports a variety of uniform broken-symmetry ground states in Landau level N=0 at integer filling factors $\nu \in [-3,4].$ When an electric potential difference (or bias) is applied between the layers at filling factors $\nu =-1,3$, the ground state evolves from an interlayer coherent state at small bias to a state with orbital coherence at higher bias where \textit{electric} dipoles associated with the orbital pseudospins order spontaneously in the plane of the layers. In this paper, we show that by further increasing the bias at these two filling factors, the two-dimensional electron gas goes first through a Skyrmion crystal state and then into an helical state where the pseudospins rotate in space. The pseudospin textures in both the Skyrmion and helical states are due to the presence of a Dzyaloshinskii-Moriya interaction in the effective pseudospin Hamiltonian when orbital coherence is present in the ground state. We study in detail the electronic structure of the helical and Skyrmion crystal states as well as their collective excitations and then compute their electromagnetic absorption.

17 pages, 17 postscript figures

References in corpus (14)

• The electronic properties of graphene
• Unconventional quantum Hall effect and Berry's phase of 2pi in bilayer graphene
• Optical and magneto-optical far-infrared properties of bilayer graphene
• Broken symmetry states and divergent resistance in suspended bilayer graphene
• Quantum Hall effect and Landau level crossing of Dirac fermions in trilayer graphene
• Skyrmion Lattice in Two-Dimensional Chiral Magnet
• Symmetry breaking of the zero energy Landau level in bilayer graphene
• Intra-Landau level Cyclotron Resonance in Bilayer Graphene
• Zero-temperature phases for chiral magnets in three dimensions
• Long range Coulomb interaction in bilayer graphene
• Anomalous Exciton-Condensation in Graphene Bilayers
• Pseudo-zero-mode Landau levels and collective excitations in bilayer graphene
• Orbital and interlayer Skyrmions crystals in bilayer graphene
• Orbital order in bilayer graphene at filling factor $\nu =-1$

Cited by in corpus (17)

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• Broken-symmetry $\nu =0$ quantum Hall states in bilayer graphene: Landau level mixing and dynamical screening
• Quantum Hall ferromagnetic phases in the Landau level N=0 of a graphene bilayer
• Structure and the Lamb-shift-like quantum splitting of the pseudo-zero-mode Landau levels in bilayer graphene
• Quantum Hall to charge-density-wave phase transitions in ABC-trilayer graphene
• Phase diagram of insulating crystal and quantum Hall states in ABC-stacked trilayer graphene
• Unique Spin Vortices in Quantum Dots with Spin-orbit Couplings
• Phase diagram of a graphene bilayer in the zero-energy Landau level
• Tuning the Topological Features of Quantum-Dot Hydrogen and Helium by a Magnetic Field
• Orbital Lamb shift and mixing of the pseudo-zero-mode Landau levels in ABC-stacked trilayer graphene
• Ising quantum Hall ferromagnetism in Landau levels $\left|N\right|\ge 1$ of bilayer graphene
• Quantum Hall ferroelectric helix in bilayer graphene
• Electromagnetic absorption and Kerr effect in quantum Hall ferromagnetic states of bilayer graphene
• Excitation Gap of Fractal Quantum Hall States in Graphene
• Charge density wave with meronlike spin texture induced by a lateral superlattice in a two-dimensional electron gas
• Interaction-enhanced electron-hole and valley asymmetries in the lowest Landau level of ABA-stacked trilayer graphene
• Landau Level Phases in Bilayer Graphene under Pressure at Charge Neutrality