  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.
