The s^±-Wave Superconductivity in the Pressurized La_4Ni_3O_10

Recently, evidence of superconductivity (SC) has been reported in pressurized La_4Ni_3O_10. Here we study the possible pairing mechanism and pairing symmetry in this material. Through fitting the density-functional-theory band structure, we provide a six-orbital tight-binding model. In comparison with the band structure of La_3Ni_2O_7, the additional non-bonding d_z^2 band is importance to the pairing mechanism here. When the multi-orbital Hubbard interactions are included, our random-phase-approximation based study yields an s^±-wave pairing with T_c significantly lower than that in pressurized La_3Ni_2O_7. The dominant FS nesting with nesting vector 𝐐_1≈ (π,π) is between the M-pocket contributed by the bonding d_z^2 band top and the local bottom regime of the non-bonding 3d_z^2 band near the Γ-point, leading to the strongest pairing gap amplitude and opposite gap signs within the two regimes. The dominant real-space pairing is the interlayer pairing between the d_z^2 orbitals. We have also studied the doping dependence of the pairing symmetry and T_c.