Electronic Raman scattering in the single layered superconduct

Electronic Raman scattering in Tl2Ba2CuO6+δ (Tl-2201) has been investigated in order to test whether the scattering cross section in high-temperature superconductors depends on the number of CuO2 planes, i.e., sheets or specific details of the Fermi surface. The polarized Raman spectra have been measured in different scattering geometries for temperatures above and below Tc. The spectral features of Tl-2201 with one CuO2 plane per unit cell are found to be similar to Tl2Ba2Ca2Cu3O10 with three CuO2 planes and those of other high-temperature superconductors with several CuO2 planes per unit cell. The peak in the B1⁢g symmetry component of the scattering intensity is found at 460 cm−1(Tc=90nK), or 430 cm−1(Tc=80nK). The B1⁢g peak positions scale with Tc, and correspond to 2Δ/kBTc=7.6±0.4. The temperature dependence of the B1⁢g scattering component of Tl-2201 (Tc=80 and 90 K) reveals a deviation from BCS behavior. The experimental data are in qualitative agreement with the calculations of Devereaux and Einzel based on the dx2−y2-wave symmetry of the order parameter used in the description of the Raman-scattering cross section.