Elastic response of the fluxoid lattice with planar pinning forces

The elastic displacements of the hexagonal flux line lattice in a type II superconductor are calculated for planar pinning forces. The nonlocal elastic behaviour, derived in a previous paper from the Ginzburg‐Landau theory, leads to strains which may become larger than the homogeneous strain of the local theory by factors up to 2x2b2/(1 − b)2, where b = B/Bc2 is the reduced induction and x is the GL parameter. At b > 0.5 the displacement of the n‐th lattice plane due to a pair of planar forces at n = 0 and at n ≫ 1 is proportional to (1 − b)−2 (−0.7)|n|. This means that the displacements are oscillatory and diverge as b → 1. The elastic response is extremely anisotropic: the maximum strain caused by the same planar force applied in two different directions may differ by a factor of 23. This result is in conflict with the homogeneous and isotropic response predicted by local elasticity theory.