Insulating states from increased kinetic energy: counterintuitive physics in the basic model of organic conductors and superconductors

The U-V model at quarter filling is the canonical model of the organic Bechgaard and Fabre salts, the first materials to exhibit a superconducting phase based on repulsive electron interactions, which is accompanied by competing magnetic phases just as for the cuprates of high-Tc superconductivity. However, just as for the doped 2D Hubbard model, the
U-V model can exhibit very rich and complicated physics, which are a challenge to treat reliably. In the presented work, we show that the U-V model can give rise to surprising physics in which an insulating state emerges from increased transverse kinetic energy, by combining large-scale DMRG results with analytic RG of bosonized models of the 2-leg U-V Hubbard ladder.