Konwersatorium im. Leopolda Infelda

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. 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, effectively modeled with classical spins. The ground state has turned out to support a vortex lattice of topological defects, Z 2 vortices, whose density is determined by the strength of the spin-orbit coupling.