2 research outputs found
Effects of a weak disorder on two coupled Hubbard chains
We consider the effect of weak nonmagnetic disorder on two chains of
interacting fermions (with and without spins) coupled by interchain hopping.
For the spinless case, interchain hopping increases localization for repulsive
interactions but {\it stabilizes} the s-wave superconducting phase for
attractive interactions. For the case with spin, the d-wave phase arising from
purely repulsive interactions in the clean system is destroyed by an
infinitesimal disorder while for attractive interactions, the s-wave
superconductivity is more resistant to disorder than in the one-chain case.Comment: 12 pages, ReVTeX ,paper submitted to PR
Spinless fermions ladders at half filling
We study a half filled ladder of spinless fermions. We show that contrarily
to a single chain, the ladder becomes a Mott insulator for arbitrarily small
repulsive interactions. We obtain the full phase diagram and physical
quantities such as the charge gap. We show that there is only a single
insulating phase for repulsive interactions, regardless of the stength of the
interchain hopping and single chain Mott gap. There is thus no
confinement-deconfinement transition in this system but a simple crossover. We
show that upon doping the system becomes a Luttinger liquid with a universal
parameter different from the one of the single chain ().Comment: 9 pages, 6 figures, uses revtex4 beta4 and natbib(included);
submitted to PR