Triplet pz-wave pairing in quasi-one-dimensional A2Cr3As3 superconductors (A = K, Rb, Cs)

We construct minimum effective models to investigate the pairing symmetry in the newly discovered quasione-dimensional superconductor K2Cr3As3. We show that a minimum three-band model based on the d(z2), d(xy), and d(x2-y2) orbitals of one Cr sublattice can capture the band structures near Fermi surfaces. In both weak and strong coupling limits, the standard random phase approximation and mean-field solutions consistently yield the triplet p(z)-wave pairing as the leading pairing symmetry for physically realistic parameters. The triplet pairing is driven by the ferromagnetic fluctuations within the sublattice. The gap function of the pairing state possesses line gap nodes on the k(z) = 0 plane on the Fermi surfaces.