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

Abstract

We study the polarization-dependent electronic Raman response of untwinned YBa${}_2$Cu${}_3$O${}_{7-\delta }$ 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.

typos corrected, 6 pages, 3 figures

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Cited by in corpus (4)

• Theory of driven Higgs oscillations and third-harmonic generation in unconventional superconductors
• Electronic and phononic Raman scattering in detwinned YBa${}_2$Cu${}_3$O${}_{6.95}$ and Y${}_{0.85}$Ca${}_{0.15}$Ba${}_2$Cu${}_3$O${}_{6.95}$: s-wave admixture to the $d_{x^2-y^2}$-wave order parameter
• Lattice dynamical signature of charge density wave formation in underdoped YBa2Cu3O6+x
• Raman response in superconducting multiorbital systems with application to nickelates