Electronic Raman scattering of Tl-2223 and the symmetry of the ̋superconducting gap

Single crystalline Tl2Ba2Ca2Cu3O10 was studied using electronic Raman scattering. The ̋renormalization of the scattering continuum was investigated as a function of the scattering geometry to determine the superconducting energy gap 2∆( $ ) k . The A1gand B2g-symmetry component show a linear frequency behavior of the scattering intensity with a peak related to the energy gap, while the B1g-symmetry component shows a characteristic behaviour at higher frequencies. The observed frequency dependencies are consistent with a dx2-y2-wave symmetry of the gap and yield a ratio of 2 7 4 0 ∆ / . k T B c = . With the polarization of the scattered and incident light either parallel or perpendicular to the CuO2-planes a strong anisotropy due to the layered structure was detected, which indicates an almost 2 dimensional ̋behavior of this system.