Seminarium Fizyki Materii Skondensowanej

Significant progress in understanding of the low-energy properties of quantum matter has been achieved using the concepts of spontaneous symmetry breaking and topological invariants separately. In this talk, I will discuss the physics of interacting systems where the relationship of these two concepts is subtler, so that the order parameters associated with the spontaneous symmetry breaking are linked to the momentum space topology. I will consider three examples of systems where such kind of interplay is important: band-inverted electron-hole bilayers, helical quantum Hall exciton condensates and flat-band superconductivity in topological semimetals. I will discuss some of the exotic properties of these systems and some general ideas for designing symmetry-broken phases by utilizing the interplay of topology and interactions.