Theory and experiment testing flux-line cutting physics

TitleTheory and experiment testing flux-line cutting physics
Publication TypeJournal Article
Year of Publication2011
AuthorsClem JR, Weigand M, Durrell JH, Campbell AM
Journal TitleSuperconductor Science & Technology
Date Published06
ISBN Number0953-2048
Accession NumberISI:000290472900002
Keywordscritical-state model, films, FORCE, HARD SUPERCONDUCTORS, ii superconductors, losses, moment, rotating magnetic-fields, surface

We discuss predictions of five proposed theories for the critical state of type-II superconductors accounting for both flux cutting and flux transport (depinning). The theories predict different behaviours for the ratio E-y/E-z of the transverse and parallel components of the in-plane electric field produced just above the critical current of a type-II superconducting slab as a function of the angle of an in-plane applied magnetic field. We present experimental results measured using an epitaxially grown YBCO thin film favouring one of the five theories, i.e. the extended elliptic critical-state model. We conclude that when the current density J is neither parallel nor perpendicular to the local magnetic flux density B, both flux cutting and flux transport occur simultaneously when J exceeds the critical current density J(c), indicating an intimate relationship between flux cutting and depinning. We also conclude that the dynamical properties of the superconductor when J exceeds J(c) depend in detail upon two nonlinear effective resistivities for flux cutting (rho(c)) and flux flow (rho(f)) and their ratio r = rho(c)/rho(f).

URL<Go to ISI>://000290472900002
Alternate JournalSupercond Sci TechSupercond Sci Tech