The interest for the theoretical description of the dimensional crossover is motivated by its several solid state realizations. In particular, there are different class of materials with strong anisotropy that display superconductivity as, for example, compounds of transition-metal dichalcogenides intercalated with organic, insulating molecules, cuprates, iron pnictides, single monolayer of FeSe and heterostructures of Bi2Te3/FeTe.
At the same time, the onset of superconductivity with the highest critical temperatures is usually found by doping a Mott insulator, where weak-coupling approaches are not applicable. For this reason the theoretical treatment of the dimensional crossover beyond the perturbative regime is a crucial ingredient for a better understanding of high-Tc superconductivity.
In the course of this project, we will study the dimensional crossover from three to two dimensions of strongly correlated systems close to a superfluid instability. We choose the attractive anisotropic Hubbard model as representative of these systems considering different hopping amplitudes along the z-axis (t⊥) and in the xy plane (t∥).
To this scope, we will exploit a quantum many-body approach (the ladder-DΓA) recently extended by the applicant and coauthors (among which the research partner of this project, Prof. A. Toschi) to treat the case of attractive interactions. The non-perturbative nature of the approach should allow for a significant improvement of the physical understanding of the dimensional crossover in superfluid/superconducting systems.
We also plan to extend the ladder-DΓA algorithm in the case of broken symmetry phases and apply it to a frustrated Hubbard model, where anisotropies manifest themselves as an emergent phenomenon due to the spin-fermion coupling in antiferromagnetic-metals.
Dates of stay:
September 1 -- 30, 2019
December 1, 2019 - February 28, 2020