The optical reflectivity and microwave conductivity are calculated for a metal that becomes superconducting below a transition temperature Tc. Electron-electron scattering on a nested Fermi surface with an isotropic weak-coupling energy gap is found to yield a reflectance at low frequencies that is compatible with measurements on superconducting YBa2Cu3O7 crystals. The computed microwave surface resistance Rs drops dramatically near Tc in accord with cuprate experiments, although the data at very low temperatures remain above the isotropic gap prediction. Our nested Fermi-liquid analysis also gives a conductivity peak below Tc. The temperature variation of the measured Rs, the conductivity line-shape data, and the reflectivity spectra are all different from the corresponding results obtained with conventional phonon damping.
ASJC Scopus subject areas
- Condensed Matter Physics