Topological Structure of the Order Parameter of Unconventional Superconductors Based on Id/I- and If/I- Elements

The superconducting order parameter (SOP) of a triplet superconductor UTe[sub.2] was constructed using the topological space group approach, in which, in contrast to phenomenological and topological approaches, the single pair function and phase winding in condensate are different quantities. The connection between them is investigated for the D[sub.2h] point group and the m[sup.′]m[sup.′]m magnetic group. It is shown how a non-unitary pair function of UTe[sub.2] can be constructed using one-dimensional real irreducible representations and Ginzburg-Landau phase winding. It is also shown that the total phase winding is non-zero in magnetic symmetry only. Experimental data on the superconducting order parameter of topological superconductors UPt[sub.3], Sr[sub.2]RuO[sub.4], LaPt[sub.3]P, and UTe[sub.2] are considered and peculiarities of their nodal structures are connected with the theoretical results of the topological space group approach.