Strain Has Major Effect on High-Temp Superconductors
Magneto-optical image of magnetic fields within a YBCO superconductor showing electrically connected grains (yellow) and grain boundaries (green) that form barriers to superconducting currents. The large reversible effect of strain observed by NIST might be due to associated changes in grain boundaries, which raise the barriers to current flow and lowering the material's current-carrying capability.
See also the NIST release, "Strain Has Major Effect on High-Temp Superconductors."
Image credit: D.C. van der Laan/NIST and J. Schwartz, NHMFL-FSU