Infrared conductivity of adx2−y2-wave superconductor with impurity and spin-fluctuation scattering

Calculations are presented of the in-plane far-infrared conductivity of a ${\mathit{d}}_{{\mathit{x}}^2\mathrm{-}{\mathit{y}}^2}$-wave superconductor, incorporating elastic scattering due to impurities and inelastic scattering due to spin fluctuations. The impurity scattering is modeled by short-range potential scattering with arbitrary phase shift, while scattering due to spin fluctuations is calculated within a weak-coupling Hubbard model picture. The conductivity is characterized by a low-temperature residual Drude feature whose height and weight are controlled by impurity scattering, as well as a broad peak centered at 4${\mathrm{\Delta }}_0$ arising from clean-limit inelastic processes. Results are in qualitative agreement with experiment despite missing spectral weight at high energies. © 1996 The American Physical Society.