Disorder, Metal-Insulator crossover and Phase diagram in high-T$_{c}$ cuprates

We have studied the influence of disorder induced by electron irradiation on the normal state resistivities $\rho $(T) of optimally and underdoped YBa$_{2}$Cu$_{3}$O$_{x}$ single crystals, using pulsed magnetic fields up to 60T to completely restore the normal state. We evidence that point defect disorder induces low $T$ upturns of $\rho $(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 $T_{c}$ 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.