Thursday 17.11.2011, 15:00-16:00 SR4


Spontaneous Fractional Quantum-Hall state in strongly correlated multiorbital systems

Maria Daghofer, IFW Dresden

Recently, several proposals have been made concerning systems, where the Fractional Quantum Hall (FQH) effect can occur on a lattice without a magnetic field. This requires nearly dispersionless bands with non-zero Chern number. We demonstrate that orbital degrees of freedom in frustrated lattice systems lead to a narrowing of topologically nontrivial bands without a need for long-range hopping. We then show that a $t_{2g}$-orbital system on a triangularlattice supports a spin-chiral magnetic ordering pattern which induces precisely the required topologically non-trivial and flat bands. Finally, we use exact-diagonalization methods to investigate the ground state of these systems and show that we indeed find signatures of a FQH ground state.