Detection of hidden orders: nontrivial phases in 1D t-J models and trivial phases in 2D systems

by Dr Elisa Fazzini (Politecnico di Torino)

Thursday 7 Jun 2018, 15:00 → 16:00 Europe/Rome

Aula Teorici (DIFA)

Nonlocal order parameters (NLOP) are an extremely powerful tool to detect hidden orders. In one dimension they are well established as order parameters for non-symmetry-breaking phases. After an overview on the mechanism by which hidden orders captured by NLOP generate gaps in 1D fermionic systems, we consider the nonlocal parity operator characterizing the Mott phase and show how to generalize it to two dimensions. Furthermore, nonlocal order parameters are strictly connected to topological properties. In fact, while the nonlocal parity signals the presence of a topologically trivial order, the Haldane string captures nontrivial phases. We show that the Haldane order exists in the doped anisotropic t-J model. On the other hand, this model is relevant in the context of hight-Tc superconductivity. In fact, besides a region with pure Haldane order, we also observe a regime with adding dominant superconducting correlations.