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

We study the interplay of Anderson localization and interaction in a two chain Hubbard ladder allowing for arbitrary ratio of disorder strength to interchain coupling. We obtain three different types of spin gapped localized phases depending on the strength of disorder: a pinned 4kF Charge Density Wave (CDW) for weak disorder, a pinned 2kF CDW π for intermediate disorder and two independently pinned single chain 2kF 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 disorder, 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 interchain hopping. PACS. 71.10Pm Fermions in reduced dimensions (anyons, composite fermions, Luttinger liquid, etc.) – 71.23.An Theories and models; localized states