13,270 research outputs found

    Topological-Fermi-Liquid to Quantum-Hall-Liquid Transitions: pp-Band and dd-Band Fermions in a Magnetic Field

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    We find that in a multi-orbital system with intraorbital and interorbital hopping integrals, the Hall conductance exhibits various topological quantum phase transitions (QPTs) induced by on-site orbital polarization: integer quantum Hall (IQH) plateau transitions, and topological Fermi liquid to IQH transitions. Such topological QPTs are demonstrated in two systems: a pp-band spinless fermionic system realizable with ultracold atoms in optical lattice, and a dd-band spinful fermionic system closely related to giant orbital Hall effects in transition metals and their compounds.Comment: 4 pages, 4 figure

    Effect of sea quarks on the single-spin asymmetries ALW±A^{W^{\pm}}_{L} in polarized pp collisions at RHIC

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    We calculate the single-spin asymmetries ALW±A^{W^{\pm}}_{L} of W±W^{\pm} bosons produced in polarized pp collisions with the valence part of the up and down quark helicity distributions modeled by the light-cone quark-spectator-diquark model while the sea part helicity distributions of the up and down quarks treated as parametrization. Comparing our results with those from experimental data at RHIC, we find that the helicity distributions of sea quarks play an important role in the determination of the shapes of ALW±A^{W^{\pm}}_{L}. It is shown that ALWA^{W^{-}}_{L} is sensitive to Δuˉ\Delta \bar u, while ALW+A^{W^{+}}_{L} to Δdˉ\Delta \bar d intuitively. The experimental data of the polarized structure functions and the sum of helicities are also important to constrain the sizes of quark helicity distributions both for the sea part and the valence part of the nucleon.Comment: 19 latex pages, 5 figures, final version for publicatio

    Edge States and Quantum Hall Effect in Graphene under a Modulated Magnetic Field

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    Graphene properties can be manipulated by a periodic potential. Based on the tight-binding model, we study graphene under a one-dimensional (1D) modulated magnetic field which contains both a uniform and a staggered component. New chiral current-carrying edge states are generated at the interfaces where the staggered component changes direction. These edge states lead to an unusual integer quantum Hall effect (QHE) in graphene, which can be observed experimentally by a standard four-terminal Hall measurement. When Zeeman spin splitting is considered, a novel state is predicted where the electron edge currents with opposite polarization propagate in the opposite directions at one sample boundary, whereas propagate in the same directions at the other sample boundary.Comment: 5 pages, 4 figure