Generic strange-metal behaviour of overdoped cuprates

We present an analysis of the temperature dependence of the zero-field in-plane resistivity ρab(T) of overdoped Tl2Ba2CuO6+δ (Tl2201). Taking our cue from earlier resistivity and angle-dependent magnetoresistance studies of Tl2201, as well as high-field measurements on La2−xSrxCuO4 (LSCO), we delineate ρab(T) into two T-dependent components below 200 K, one linear in temperature, the other quadratic. As found in LSCO, the T-linear component α1(0) is finite for all superconducting samples, its magnitude scaling with the transition temperature Tc. By contrast, the T2 coefficient α2(0) is essentially doping independent. Such an extended regime (in doping) of T-linear resistivity at low T is at odds with conventional quantum critical scenarios involving the collapse of an ordered phase, possibly associated with the normal state pseudogap, to 0 K at a critical doping level. Its confirmation in Tl2201, whose electronic state (as revealed by quantum oscillation experiments) is highly homogeneous over hundreds of unit cells, appears to rule out phase separation or electronic inhomogeneity as the origin of this extended critical behaviour.