Breakdown of Landau Theory in Overdoped Cuprates near the Onset of Superconductivity

We use the functional renormalization group to analyze the temperature dependence of the quasi-particle scattering rates in the two-dimensional Hubbard model below half-filling. Using a band structure appropriate to overdoped Tl2Ba2CuO(6+x) we find a strongly angle dependent term linearly dependent on temperature which derives from an increasing scattering vertex as the energy scale is lowered. This behavior agrees with recent experiments and confirms earlier conclusions on the origin of the breakdown of the Landau Fermi liquid near the onset of superconductivity.