Fabrizio Dolcini
Politecnico di Torino
Ground state phase diagram of exactly solved electronic models
We describe a general method to study the ground state phase
diagram of models on chains whose Hamiltonian acts as a generalized permutator.
The integrability of these models has recently been proved[1]. The method,
based on the appropriate interpretation of the so called Sutherland's species[2],
yields (under described conditions) a reduction of the effective Hilbert
space. In particular, we derive[3] the phase diagrams of two new 1-$d$
extended Hubbard models, as a function of the electron filling ($n$)
and the on-site Coulomb repusion ($U$). The first one exhibits a band-controlled
insulator-superconductor transition at half-filling for the unusually high
value $U_c=6 t$; the second one is characterized by a filling-controlled
metal-insulator transition between two finite regions of the diagram. Further
physical features are discussed.