Departures from Linear-in-T resistivity as a function of doping in cuprate superconductors

A linear-in-T or “strange-metal” resistivity is one of the hallmark features of cuprate superconductors near optimal doping, with this behavior unexpected from the conventional Fermi liquid theory of the electron gas.  In contrast, at very high doping levels, it is generally agreed that the Fermi liquid (quadratic) scattering is recovered, though the way in which this recovery occurs is not well understood or characterized.  Here, we carefully study this evolution in a series of cuprate superconductors, with principle focus on the Bi₂Sr₂CaCu₂O_8+δ family of bilayer superconductors. We fit the resistivity with various parameterizations, check for scaling of parameters, and do a careful comparison to scattering rates observed from ARPES.  Our results show a clear break in parameters at a critical doping point near p=0.22 – a similar doping level obtained from a range of other experiments. The success of our parameterizations suggests a more general model for describing the energy and temperature dependences of the electronic interactions in cuprate superconductors.