In-Field Critical Current of Type-II Superconductors Caused by Strain from Nano-scale Columnar Inclusions

The results of a linear elasticity analysis yields that nano-rod inclusions aligned along the c axis of a thin film of YBa2Cu3O{7-delta}, such as BaZrO3 and BaSnO3, squeeze that matrix by pure shear. The sensitivity of the superconducting critical temperature in that material to the latter implies that the phase boundary separating the nano-rod inclusion from the superconductor acts as a collective pinning center for the vortex lattice that appears in external magnetic field. A dominant contribution to the in-field critical current can result. The elasticity analysis also finds that the growth of nano-rod inclusions can be weakly metastable when the inclusion is softer than the matrix.