Superconducting gap symmetries in YBa2Cu3O7−δ compatible with electronic Raman efficiencies and the local-density-approximation band structure

Abstract

Superconductivity induced absolute electronic Raman efficiencies are presented for single-domain YBa2Cu3O7−δ in a-b plane polarization geometries and compared with spectra calculated from gauge invariant theory using realistic Raman vertices derived from the local-density-approximation band structure. Effective mass fluctuations, screening, gap size, and anisotropy on the multisheeted Fermi surface are systematically investigated. It is argued that the observed anisotropy of the A1g, B2g, and B1g spectra requires two different gaps on the CuO2 plane Fermi surfaces of even and odd parity. Respective time reversal invariant gaps of B1g and A1g symmetry (e.g., Δeven=dx2−y2, Δodd=0.5is) or of A1g and A2g symmetry (e.g., Δeven=s|x2−y2|, Δodd=sxy(x2−y2)) are found compatible with the Raman data, band-structure calculations, and with corner-superconducting quantum interference device and c-axis tunneling results. © 1996 The American Physical Society.

Source-reported materials — not catalogue approval

Similar papers