Abstract
Effects of the interladder one-particle hopping, t⊥, on the low-energy asymptotics of a weakly coupled Hubbard ladder system have been studied, based on the perturbative renormalization-group approach.We found that for finite intraladder Hubbard repulsion, U, thereexists a crossover value of the interladder one-particle hopping, t⊥ c.For 0⊥⊥ c, the spin gap metal (SGM) phase of theisolated ladder transits at a finite transition temperature, Tc, to the d-wave superconducting (SCd) phase via a two-particle crossover.In the temperature region, Tc, interladder coherent Josephson tunneling of the Cooper pairs occurs, while the interladder coherent one-particle process is strongly suppressed.For t⊥ c⊥, around a crossover temperature, Tcross, the system crosses over to the two-dimensional (2D)phase via a one-particle crossover. In the temperature region, Tcross, the interladder coherent band motion occurs.
