Effect of stress along the ab plane on the ${\mathit{J}}_{\mathit{c}}$ and ${\mathit{T}}_{\mathit{c}}$ of ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ thin films

We studied the influence of elastic stress along the ab plane (${\mathrm{\sigma }}_{\mathit{a}\mathit{b}}$) on the critical current density (${\mathit{J}}_{\mathit{c}}$) and transition temperature (${\mathit{T}}_{\mathit{c}}$) of epitaxial c-axis-oriented ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ thin films. We observed reversible and reproducible increases (with compression) and decreases (with extension) of ${\mathit{J}}_{\mathit{c}}$ and ${\mathit{T}}_{\mathit{c}}$ from their equilibrium values. By comparing ${\mathit{dT}}_{\mathit{c}}$/d${\mathrm{\sigma }}_{\mathit{a}\mathit{b}}$=0.045–0.050 K/kbar with the results of hydrostatic-pressure and thermodynamic experiments reported in the literature, we conclude that pressure-induced changes in the ab plane completely account for the changes in ${\mathit{T}}_{\mathit{c}}$ (within our experimental uncertainty). We also show that the mismatch strain between film and substrate does not substantially affect the change in ${\mathit{T}}_{\mathit{c}}$ caused by the external stress.