d-wave pairing in tetragonal superconductors

Abstract

Using group-theoretical methods, we classify into 11 symmetry classes all translationally invariant singlet-paired superconducting-gap functions whose quasiparticle energy spectrum preserves the symmetry of a tetragonal crystal. We show that for the gap function of symmetry Δd+(coskx-cosky) the two logarithmic singularities in the density of states as a function of energy are a robust consequence of changes in topology of the surfaces of constant quasiparticle energy. Removing the node in this gap function by adding an imaginary component of symmetry iΔd− sinkx sinky results in the only possible nodeless gap function that does not involve s-wave pairing, and hence is the only nodeless singlet superconductor that is not suppressed by a Hubbard-type repulsion. We discuss the possible relation to ab-plane tunneling experiments in the high-Tc compound Bi2Sr2CaCu2O8.

Source-reported materials — not catalogue approval

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