Authors: A. Stangl, A. Palau, G. Deutscher, X. Obradors and T. Puig
Scientific Reports volume 11, Article number: 8176 (2021)
Abstract: The functional properties of cuprates are strongly determined by the doping state and carrier density. We present an oxygen doping study of YBa2Cu3O7-δ (YBCO) thin films from underdoped to overdoped state, correlating the measured charge carrier density, , the hole doping, p, and the critical current density, . Our results show experimental demonstration of strong increase of with , up to Quantum Critical Point (QCP), due to an increase of the superconducting condensation energy. The ultra-high achieved, 90 MA cm−2 at 5 K corresponds to about a fifth of the depairing current, i.e. a value among the highest ever reported in YBCO films. The overdoped regime is confirmed by a sudden increase of , associated to the reconstruction of the Fermi-surface at the QCP. Overdoping YBCO opens a promising route to extend the current carrying capabilities of rare-earth barium copper oxide (REBCO) coated conductors for applications.