Abstract
We have studied the influence of disorder induced by electron irradiation on the normal-state resistivities ρ(T) of optimally and underdoped YBa2Cu3Ox single crystals, using pulsed magnetic fields up to 60 T to completely restore the normal state. We evidence that point defect disorder induces low-T upturns of ρ(T) which saturate in some cases at low T in large applied fields as would be expected for a Kondo-like magnetic response. Moreover, the magnitude of the upturns is related to the residual resistivity, that is to the concentration of defects and/or their nanoscale morphology. These upturns are found quantitatively identical to those reported in lower-Tc cuprates, which establishes the importance of disorder in these supposedly pure compounds. We therefore propose a realistic phase diagram of the cuprates, including disorder, in which the superconducting state might reach the antiferromagnetic phase in the clean limit.