Magnetic properties of oxygen-depleted YBa2Cu3O7-y single crystals.

Abstract

Magnetic properties and flux pinning of oxygen-deficient ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{y}}$ single crystals have been studied. The superconducting transition temperature and inductive critical current density decrease as the level of oxygen depletion increases. No obvious enhancement in the pinning strength was found in the oxygen-depleted ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{y}}$ system for the applied field along the c axis. We attribute this absence of enhanced pinning to the mismatch of the oxygen vacancy size with the superconducting coherence length over the entire superconducting regime.