Grain boundaries can be a significant barrier for current flow in high temperature superconducting (HTS) thin films. We show that an applied compressive strain causes a remarkable increase in critical current density (Jc,GB) in thin film YBa2Cu3O7-δ (YBCO) grain boundaries. The data presented here clearly show that the strain dependence of Jc,GB is somewhat surprisingly identical to that of the intragrain critical current density (Jc), contrary to present understanding. A relatively straightforward model is shown to describe and predict how strain affects the current transfer in grain boundaries, where it provides an estimate of the lattice strain at the grain boundary.
Citation: Physical Review Letters
Pub Type: Journals
superconductivity, grain boundaries, strain, critical current density, thin films