Disorder, metal-insulator crossover and phase diagram in high-T_c cuprates

¹  Service de Physique de l'Etat Condensé (CNRS URA 2464), CEA Saclay - 91191 Gif-sur-Yvette cedex, France
²  Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris-Sud - 91405 Orsay, France
³  National High Magnetic Field Laboratory, Los Alamos National Laboratory - Los Alamos, NM 87545, USA
⁴  Laboratoire National des Champs Magnétiques Pulsés, UMR CNRS-UPS-INSA 5147 - Toulouse, France

Corresponding author: florence.albenque-rullier@cea.fr

Received: 19 October 2007
Accepted: 4 December 2007

Abstract

We have studied the influence of disorder induced by electron irradiation on the normal-state resistivities of optimally and underdoped YBa₂Cu₃O_x 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 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.