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Electronic correlations have long been known to fundamentally affect a material's property. I will discuss situations, where they can induce topologically nontrivial electronic states. Interaction between itinerant carriers and localized spins on frustrated lattices can stabilize phases that are in many respects similar to a Landau level, as a non-coplanar spin background gives the electrons a complex phase analogous to that induced by a magnetic field. If the bands are nearly flat, longer-range Coulomb repulsion can then induce states that are like lattice-analogs of fractional Quantum-Hall states, but do not require an external magnetic field. I will also discuss Mott insulators with spin-orbit coupling, where excitations then have combined spin and orbital character. We have investigated effective classical spin model for spin-orbit coupled Mott insulators. The ground state has turned out to support a vortex lattice of topological defects, Z2 vortices, whose density is determined by the strength of the spin-orbit coupling.

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Dr. Maria Daghofer, IFW Dresden
Seminarraum des II. Physikalischen Instituts
Contact: not specified