title: Strongly Enhanced Superconductivity in Coupled t-J Segments.
abstract: The t-J Hamiltonian is one of the cornerstones in the theoretical study of strongly correlated copper-oxide based materials. Using the density-matrix renormalization group method we obtain the phase diagram of the one-dimensional t-J chain in the presence of a periodic hopping modulation, as a prototype of coupled-segment models. While in the uniform 1D t-J model the near half-filling superconducting state dominates only at unphysically large values of the exchange coupling constant J/t>3; we show that a small hopping and exchange modulation very strongly reduces the critical coupling to be as low as J/t∼1/3--well within the physical regime. The phase diagram as a function of the electron filling also exhibits metallic, insulating line phases and regions of phase separation. We suggest that a superconducting state is easily stabilized if t-J segments creating local spin-singlet pairing are coupled to each other--another example is the ladder system.
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany.
authors.forename: Sahinur
authors.initials: S
authors.lastname: Reja
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany.
authors.forename: Jeroen
authors.initials: J
authors.lastname: van den Brink
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany.|Institute for Theoretical Physics, TU Dresden, 01069 Dresden, Germany.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nishimoto