SPATIAL STRUCTURE OF THE SUPERCONDUCTING PHASE IN HEAVY-FERMION SYSTEMS AND ANOMALIES IN THE EXCITATION SPECTRUM

A degenerate superconducting phase in a metal with strong spin-orbital coupling may have a domain structure at low temperatures. The domain walls (of width ζ EQ υF/Δ0) carry a finite density of states N(0) mkF/π2 per unit volume, which in turn results in the presence of a linear term γT in the electronic specific heat Ce(T). With the help of the Atiyah-Singer theorem, this can be proved for a wide class of domain structures. The simplified case where the expression for the superconducting order parameter of a tetragonal (e.g., U-Fe, Ce-Cu-Si) or hexagonal (U-Pt) crystal is reduced to a single two-dimensional representation is considered.