Dominance of Antinodal Quasiparticles on the Transport Properties of Heavily Overdoped High-T_c Cuprates: Infrared-Reflectance Spectra

The infrared reflectance spectrum up to 2500cm^-1 for heavily overdoped Tl-2201 at 300K has been analysed under the semiclassical approximation. In this approach, we use two independent sets of parameters to fit the reflectance: the momentum-dependent Fermi velocity v_k and the momentum-dependent scattering rateτ^-1(ε_k). Unlike the case at optimal doping in which the transport properties are dominated by the nodal quasi-particles (QPs), both the lifetime and the Fermi velocity of the QPs in the antinodal region near the Fermi surface increase remarkably for the heavily overdoped samples. Our fitting results indicate that the antinodal QPs tend to dominate the transport properties in heavily overdoped high-Tc cuprates.