Robustness of superconductivity in the two-orbital Hubbard chain*

Motivated by recent findings of both spin-singlet and spin-triplet pairing in one-dimensional multiorbital Hubbard models at intermediate interaction strengths [N. Patel et al., npj Quantum Mater. 5, 27 (2020)], we study the robustness of the superconducting phases in the two-orbital Hubbard chain. At half-filling, the model maps to the Haldane spin-1 chain in the limit of large Hubbard U and Hund's coupling J_H, whereas superconductivity emerges upon hole doping. Here we consider the system away from the ideal limit of unit hopping and  degenerate orbitals. Using DMRG calculations we explore the effects of interorbital hopping, detuned intraorbital hopping, and crystal fields expected to be present in real materials. We find that while these effects are all detrimental to the emergence of superconductivity, the presence of on-site easy-plane anisotropy tends to promote hole pairing. We discuss their impact on the pairing symmetry and phase diagram.