Competition of disorder and interchain hopping in a two-chain Hubbard model

We study the interplay of Anderson localization and interaction in a two ch ain Hubbard ladder allowing for arbitrary ratio of disorder strength to int erchain coupling. We obtain three different types of spin gapped localized phases depending on the strength of disorder: a pinned 4k(F) Charge Density Wave (CDW) for weak disorder, a pinned 2k(F) CDWpi for intermediate disord er and two independently pinned single chain 2k(F) CDW for strong disorder. Confinement of electrons can be obtained as a result of strong disorder or strong attraction. We give the full phase diagram as a function of disorde r, interaction strength and interchain hopping. We also study the influence of interchain hopping on localization length and show that localization is enhanced by a small interchain hopping but suppressed by a large interchai n hopping.