Superconducting paring induced by the Mott stripe in t-J ladders

Stripe formation is ubiquitous in the doped cuprates family and in corresponding numerical studies on 2D lattices. However, the complex competition of different orders makes it difficult to understand how they precisely affect the superconducting pairing in high-temperature superconductors. Alternatively, we study a simplified ladder system with doped outer-legs and a Mott stripe core, produced by the interplay of strong repulsion and the large negative on-site potential in the inner legs. By using the density matrix renormalization group method in 4-leg ladders, we show that, for anisotropic exchange couplings, a novel singlet-pair superconducting phase occurs with the fermions in the pairs residing on different sides of the Mott insulating stripe. In this phase, the binding energy is negative and the interleg singlet-pair correlation function decays algebraically with distance, in contrast to other correlations that are exponentially decaying. We expect our findings to shed light on the pairing mechanisms for the high-temperature superconductivity, and potentially highlight novel types of pairing mechanisms in AMO experiments. Part of this work is published as Phys. Rev. B 98, 121112(R) (2018).