L.V. Gasparov, P. Lemmens, M.B. Brinkmann,
N.N. Kolesnikov, G. Guntherodt.
Electronic Raman scattering in the single - CuO2
layered superconductor Tl2Ba2CuO6+d.
Electronic Raman scattering in Tl2Ba2CuO6+d
(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 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
which three CuO2 planes and those of
other high - temperature superconductors with several CuO2
planes per unit cell. The peak in the B1g symmetry component
of the scattering intensity is found at 460 cm-1 (Tc=90
K), or 430 cm-1 (Tc=80 K). The B1g
peak positions scale with Tc, and correspond to
2D/kBTc = 7.6±0.4.
The temperature dependence of the B1g 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 d x2-
y2 wave symmetry of the order parameter
used in the description of the Raman-scattering cross section.