On flux pinning by point pinning centres in Type‐II superconductors

The maximal flux line displacement s(O) caused by a point force is calculated from the correct elastic properties of the flux line lattice, which were derived in a provioous paper. For bx 2 > (1 b)(x Ginsburg‐Landau parameter, b B/H c2 reduced induction) non‐local effects become important and lead to an s(O) larger than the result of local theory of elasticity by a factor \documentclass{article}\pagestyle{empty}\begin{document}$ {x \sqrt {b/2(1 - b)} }$\end{document} or even more. As a consequence, the volume pinning force P v for a depinning process becomes larger by this factor. In particular, near H< c2 , P v ∼ \documentclass{article}\pagestyle{empty}\begin{document}$ {\sqrt {1 - b} }$\end{document} is obtained rather than P v ∼(1 − b) as obtained by previous authors.