Shape Distortion by Irreversible Flux-Pinning-Induced Magnetostriction

TL;DR

This paper provides exact analytical results on how flux pinning causes irreversible shape distortions in type-II superconductors, revealing new deformation modes and implications for experimental measurements.

Contribution

It introduces new modes of irreversible deformation in superconductors with non-circular cross-sections, extending understanding beyond circular geometries.

Findings

Square cross-section deforms with significant distortion

Multiple distortion modes including concave and convex shapes

Implications for dilatometric measurements on superconducting crystals

Abstract

Exact analytical results are obtained for the flux-pinning-induced magnetostriction in cylindrical type-II superconductors placed in parallel magnetic field. New modes of irreversible deformation are found: In contrast to the circular cylinder where shape is conserved, it is shown that a square cross-section deforms with considerable distortion. During a field cycle both concave, convex, and even more complicated distortions are predicted. Strong implications for dilatometric measurements on crystals are emphasized. The main results are valid for any critical-state model, j_c = j_c(B).