Insights from specific heat of overdoped cuprates*

Overdoped cuprates are often touted as exhibiting more or less “conventional Fermi-liquid-like behaviour” in the normal state. Yet as T_c goes to zero in heavily overdoped cuprates, unconventional behaviour is still observed in several superconducting state properties. For example, the low-temperature electronic specific heat develops an increasingly large residual component and the height of the anomaly at T_c decreases. This is accompanied by an unexpected scaling of the zero-temperature superfluid density with T_c, which should be constant within a conventional BCS picture. By considering lifetime effects I show that these observations can be explained by temperature-dependent scattering in the presence of a d-wave energy gap, and a decreasing pairing interaction strength with doping.