Behavior of Bulk High-temperature Superconductors of Finite Thickness Subjected to Crossed Magnetic Fields : Experiment & Model.
Behavior of Bulk High-temperature Superconductors of Finite Thickness Subjected to Crossed Magnetic Fields : Experiment & Model
Bulk melt-processed (RE)-Ba-Cu-O superconductors (where RE denotes a Rare Earth ion) are able to trap significant magnetic fields, which gives rise to the possibility of high-field permanent magnet-like devices.Applying a magnetic field in a direction transverse to that of the sample magnetization in a bulk superconductor may cause significant decay of the trapped field,which could result in the failure of such devices in practical applications. The study of superconductors in the "crossed magnetic field" configuration is therefore of practical as well as of fundamental interest.
In the present work, crossed magnetic field effects on bulk high-temperature superconductors have been studied both experimentally and numerically. In particular, the spatial distribution of the trapped magnetic induction parallel to the c-axis was recorded using a Magneto-Optic Imaging (MOI) system before and after transverse fields are applied. Figure (a) shows the initial MO image. The magnetic flux profiles recorded after the application of two transverse magnetic field cycles (directed along the y direction) are shown in Fig. (b). The principal features of the experimental data could be reproduced qualitatively using a two-dimensional finite-element numerical model based on an E-J power law and in which the current density flows perpendicularly to the plane within which the two components of magnetic field are varied [Fig. (c)].
The results of this study show that the suppression of the magnetic moment under the action of a transverse field can be predicted successfully by ignoring the existence of flux-free configurations or flux-cutting effects.
Ph. Vanderbemden, Z. Hong, T. A. Coombs,
S. Denis, M. Ausloos, J. Schwartz, I. B. Rutel, N. Hari Babu,
D. A. Cardwell and A. M. Campbell, Phys. Rev. B (2007)
Part of this work was supported by the NHMFL Visitor’s Program, which is supported by the U.S. National Science Foundation.