SHAPE DISTORTION BY IRREVERSIBLE FLUX-PINNING-INDUCED MAGNETOSTRICTION

Exact analytical results are obtained for the flux-pinning-induced mag netostriction in cylindrical type-II superconductors placed in paralle l magnetic fields. New modes of irreversible deformation are found: In contrast to the circular cylinder where shape is conserved, it is sho wn that a square cross section deforms with considerable distortion. D uring a field cycle, concave, convex, and even more complicated distor tions are predicted. Strong implications for dilatometric measurements on crystals are emphasized. The main results are valid for any critic al-state model, j(c) = j(c)(B).