Disorder and transport in cuprates: Weak localization and magnetic contributions - art. no. 157001

We report resistivity measurements in underdoped YBa2Cu3O6.6 and overdoped Tl2Ba2CuO6+x, single crystals in which the concentration of defects in the CuO2 planes is controlled by electron irradiation. Low T upturns of the res istivity are observed in both cases for large defect content. In the Tl com pound the decrease of conductivity scales as expected from weak localizatio n theory. On the contrary, in YBa2Cu3O6.6 the much larger low T contributio n to the resistivity is proportional to the defect content and might then b e associated with a Kondo-like spin flip scattering term. This would be con sistent with the results on the magnetic properties induced by spinless def ects.