Flux-pinning-induced stress and magnetostriction in bulk superconductors

Abstract

The development of bulk high-temperature superconductors (HTSs) and their applications has today come to a point where the mechanical response to high magnetic fields may be more important than their critical-current density and large-grain property. Reviewed in this article are the recent studies of the magneto-elastic effects which are caused by flux pinning in the superconductors. This includes the work on the giant irreversible magnetostriction and internal stress, which often cause fatal cracking of the HTS bulks as they become magnetized. The cracking is a problem that today accompanies the quest for the highest trapped field values, and the latest development in this area is also presented. While the first part is an overview of experimental efforts, the second summarizes the work done to model the pinning-induced stress and strain under various magnetic and geometrical conditions.

Anisotropic thermal expansion and magnetostriction of YNi2B2C single crystals

“…Magnetostriction in superconducting state depends on number of parameters, including the extrinsic ones, like shape of the sample, pinning strength and its field dependence [24,25,26,27]. Moreover, irreversible flux pinning induced magnetostriction causes (geometrydependent) shape distortions [26,28] that add additional requirements on mounting of the sample in the experimental cell for detailed study of the critical superconducting state via magnetostriction. Here we will just mention that in both samples the magnetostriction in the intermediate superconducting state is high (∆L max /L 0 > 1 · 10 −7 ), significantly higher than that seen for the polycrystalline sample [5], in both samples the features associated with peak effect [27] or "dip" in magnetization [29] are apparently seen, with some structure for the sample B.…”

Effect of Transport Current on the Pinning Induced Magnetostriction of Type-II Superconductors

“…As verified by a great number of papers [11][12][13][14][15][16][17][18][19][20][21][22][23][24], this results in an anomalous irreversible magnetostriction and shape distortion in type-II superconductors with strong pinning. The objective of this work is to provide a model to calculate the internal stress and magnetostriction that occurs when a current is transported through a superconductor in absence and presence of the external field in slab geometry within the critical state model.…”

Kim model for flux-pinning-induced stress in a long cylindrical superconductor

“…In addition, they obtained the analytical solutions of the magnetoelastic three-dimensional problem in prismatic slabs with a rectangular and a square cross section. 16 Nabialek et al 17 attempted to calculate the pinning induced magnetostriction for different sample shapes. Inanir et al 18 and Xue et al 19 considered the effect of the viscous flux flow and the flux creep on the magnetostriction in an infinite slab.…”

“…[28][29][30][31][32][33][34] Johansen 28 and Yong et al 29 studied the flux-pinning-induced stress in a long rectangular slab for different critical state models, respectively. In addition, Johansen 30 theoretically investigated the mechanical stress enhanced by the hole in a cylindrical HTS with a concentric hole, and the effect of an elliptic hole on the pinning-induced stress is also studied by using the finite element method.…”