Measurements of reflectivity, R, as a function of temperature, T, and frequency, ω, in crystals of Ba2YCu3O7-δ, with σ ≅ 0.1, 0.3, and 0.8, are reported. The frequency dependent conductivity, σ(ω, T), obtained by analysis of R extrapolates at low ω to values consistent with previously reported σ(O,T). To explain the shape of σ(ω, T) requires the quasiparticle mass and lifetime to be strongly ω-dependent, withh¯/τ ≈ 2kBT and m*/mo ≈ 7 at low ω, crossingg over toh¯/τ ≈ 0.35 eV and m*/mo ≈ 1 forh¯/τ 〉 0.3 eV.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering