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Screening in (d+s)-wave superconductors: Application to Raman scattering

Andreas P. Schnyder·Christopher Mudry·Dirk Manske
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Abstract

We study the polarization-dependent electronic Raman response of untwinned YBa$_2$Cu$_3$O$_{7-δ}$ superconductors employing a tight-binding band structure with anisotropic hopping matrix parameters and a superconducting gap with a mixing of $d$- and s-wave symmetry. Using general arguments we find screening terms in the $B^{\}_{1g}$ scattering channel which are required by gauge invariance. As a result, we obtain a small but measurable softening of the pair-breaking peak, whose position has been attributed for a long time to twice the superconducting gap maximum. Furthermore, we predict superconductivity-induced changes in the phonon line shapes that could provide a way to detect the isotropic s-wave admixture to the superconducting gap.

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Andreas P. Schnyder, Christopher Mudry, Dirk Manske. 2007-06-01. Screening in (d+s)-wave superconductors: Application to Raman scattering. https://doi.org/10.1103/physrevb.75.174525

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