53 research outputs found
Critical currents in vicinal YBaCuO films
Most measurements of critical current densities in
YBaCuO thin films to date have been performed on films
where the \textit{c}-axis is grown normal to the film surface. With such films,
the analysis of the dependence of on the magnetic field angle is complex.
The effects of extrinsic contributions to the angular field dependence of
, such as the measurement geometry and disposition of pinning centres, are
convoluted with those intrinsically due to the anisotropy of the material. As a
consequence of this, it is difficult to distinguish between proposed FLL
structure models on the basis of angular critical current density measurements
on \textit{c}-axis films. Films grown on mis-cut (vicinal) substrates have a
reduced measurement symmetry and thus provide a greater insight into the
critical current anisotropy. In this paper previous descriptions of the
magnetic field angle dependence of in YBaCuO are
reviewed. Measurements on YBaCuO thin films grown on a
range of vicinal substrates are presented and the results interpreted in terms
of the structure and dimensionality of the FLL in YBaCuO.
There is strong evidence for a transition in the structure of the flux line
lattice depending on magnetic field magnitude, orientation and temperature. As
a consequence, a simple scaling law can not, by itself, describe the observed
critical current anisotropy in YBaCuO. The experimentally
obtained behaviour of YBCO is successfully described in terms of
a kinked vortex structure for fields applied near parallel to the \textit{a-b}
planes.Comment: 10 pages, 12 figures, Submitted to PR
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