By modelling a flux line as a line of centers of dilatation, it was shown that - within linear elasticity and continuum theory - the elastic interaction between a flux line and a point defect in an isotropic superconducting solid was due entirely to its surface. This surface effect, in a superconducting film with two parallel free surfaces, was considered in detail. The analysis showed that the absolute value of the interaction energy and the interaction force between a flux line and a point defect decreased rapidly with increasing distance from the point defect to the free surface and to the flux line. The interaction between a flux line and a point defect was found to be strong only when the defect was close to the flux line and to the free surface.

Flux Line-Point Defect Interactions in Type II Superconducting Films. H.Y.Yu, C.S.Pande: Journal of Applied Physics, 2008, 104[4], 043917