Theory and experiment testing flux-line-cutting physics

Abstract

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 favoring one of the five theories: the extended elliptic critical-state model. We conclude that when the current density $\mathbf{J}$ is neither parallel nor perpendicular to the local magnetic flux density $\mathbf{B}$, 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 $r={\rho }_c/{\rho }_f$.

19 pages, 12 figures, submitted to Supercond. Sci. Technol

References in corpus (7)

• Reconnection Dynamics for Quantized Vortices
• The critical current of YBa2Cu3O7-d Low Angle Grain Boundaries
• General critical states in type-II superconductors
• "Unusual" critical states in type-II superconductors
• Suppression of vortex channeling in meandered YBa2Cu3O7-d grain boundaries
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Cited by in corpus (7)

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• Parallel magnetic field suppresses dissipation in superconducting nanostrips
• Theory of flux cutting and flux transport at the critical current of a type-II superconducting cylindrical wire
• Cross-field demagnetization of stacks of tapes: 3D modelling and measurements
• Material laws and related uncommon phenomena in the electromagnetic response of type-II superconductors in longitudinal geometry
• Force-free state in a superconducting single crystal and angle-dependent vortex helical instability
• Flux-cutting and flux-transport effects in type-II superconductor slabs in a parallel rotating magnetic field