The $t\text{−}J$ 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 $t\text{−}J$ chain in the presence of a periodic hopping modulation, as a prototype of coupled-segment models. While in the uniform 1D $t\text{−}J$ 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 $J/t\sim 1/3$—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 $t\text{−}J$ segments creating local spin-singlet pairing are coupled to each other—another example is the ladder system.

• Received 14 September 2015

DOI:https://doi.org/10.1103/PhysRevLett.116.067002