We report results of Raman-scattering experiments on electronic and phononic excitations in single-crystalline ${\mathrm{Tl}}_2$${\mathrm{Ba}}_2$${\mathrm{CuO}}_6$ with one Cu-O layer and a ${\mathit{T}}_{\mathit{c}}$ of 80 K. The electronic scattering is similar to that in other Cu-O compounds, revealing a symmetry-dependent carrier relaxation rate above ${\mathit{T}}_{\mathit{c}}$ and a characteristic redistribution of scattering intensity below ${\mathit{T}}_{\mathit{c}}$. The maximum pairing energy 2${\mathrm{\Delta }}_0$ estimated from the spectra is between 8 and 9${\mathit{kT}}_{\mathit{c}}$. In addition to the Raman-allowed phonons several new lines and bands are found which we believe to originate from the reduced symmetry of the Tl-O layers. The intensities of all phonon lines depend sensitively on the excitation wavelength.

• Received 4 November 1992

DOI:https://doi.org/10.1103/PhysRevB.47.3450