Robust Superconductivity in Quasi-one-dimensional Multiband Materials

Recently it has been demonstrated that the pair-exchange coupling of quasi-one-dimensional (Q1D) bands with conventional higher-dimensional bands in one multiband superconducting material can result in the formation of a robust aggregate pair condensate. In particular, it has been found that the Q1D thermal pair fluctuations are suppressed in the presence of deep conventional band(s), for which the Fermi level is much larger than the characteristic cutoff energy. Here we report that the impact of the Q1D fluctuations is significantly weakened even in the presence of nearly shallow higher-dimensional band(s), which shed new light on the robust superconducting state observed in emerging chain-like-structured superconducting materials A₂Cr₃As₃ (A = K, Rb, Cs).