Recent experiments in multiband Fe-based and heavy-fermion superconductors have challenged the long-held dichotomy between simple s- and d-wave spin-singlet pairing states. Here, we advance several time-reversal-invariant irreducible pairings that go beyond the standard singlet functions through a matrix structure in the band/orbital space, and elucidate their naturalness in multiband systems. We consider the sτ₃ multiorbital superconducting state for Fe-chalcogenide superconductors. This state, corresponding to a d + d intra- and inter-band pairing, is shown to contrast with the more familiar d + id state in a way analogous to how the B- triplet pairing phase of ³He superfluid differs from its A- phase counterpart. In addition, we construct an analog of the sτ₃ pairing for the heavy-fermion superconductor CeCu₂Si₂, using degrees-of-freedom that incorporate spin-orbit coupling. Our results lead to the proposition that d-wave superconductors in correlated multiband systems will generically have a fully-gapped Fermi surface when they are examined at sufficiently low energies.

最近在多基铁基和重费米子超导体上进行的实验挑战了简单的s波和d波自旋单重态配对状态之间长期存在的二分法。在这里，我们通过频带/轨道空间中的矩阵结构，推进了超越标准单重态函数的几个时间不可逆不可约配对，并阐明了它们在多频带系统中的自然性。我们认为，小号τ ₃ multiorbital超导的铁硫属化物超导体状态。该状态对应于d  +  d带内和带间配对，显示为与更熟悉的d  + i d形成对比。以类似于³ He超流体的B-三重态配对相与其A-相配对相异的方式表示。此外，我们构建的模拟小号τ ₃配对的重费密子超导体CECU ₂的Si ₂，使用度的自由度并入自旋轨道耦合。我们的结果导致这样的假设，即当在足够低的能量下进行检查时，相关多频带系统中的d波超导体通常将具有完全带隙的费米表面。