Effects of Zn doping on the pinning potential and the glass-liquid transition temperature of YBa2Cu3O6+δ films

Abstract

A pristine YBa2Cu3O6+δ film as well as two Zn-doped YBa2(Cu1−x Zn x )3O6+δ films with doping levels x of 0.2 % and 0.4 %, respectively, grown epitaxially on SrTiO3 single crystalline substrates by pulsed laser deposition, were investigated regarding the effect of the doping on the glass-liquid transition line and the pinning potential distribution. Zn doping did not show any effect on the shape of the transition line but caused a suppression of the transition temperature T GL of about 16 K%−1. Although the doping did not lead to an additional pinning effect, the increase of the critical current density j c towards lower temperatures is mainly driven by the variation of the threshold critical current density, j cm. The width of the critical current density distribution j 0 saturates at low temperatures and only drops above ~ 0.9T GL.