title: Dramatic role of critical current anisotropy on flux avalanches in MgB2 films.
abstract: Anisotropic penetration of magnetic flux in MgB(2) films grown on vicinal sapphire substrates is investigated using magneto-optical imaging. Regular penetration above 10 K proceeds more easily along the substrate surface steps, the anisotropy of the critical current being 6%. At lower temperatures the penetration occurs via abrupt dendritic avalanches that preferentially propagate perpendicular to the surface steps. This inverse anisotropy in the penetration pattern becomes dramatic very close to 10 K where all flux avalanches propagate in the strongest pinning direction. The observed behavior is fully explained using a thermomagnetic model of the dendritic instability.
authors.affiliation: Max-Planck-Institut für Metallforschung, Heisenbergstrasse. 3, D-70569 Stuttgart, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Albrecht
authors.forename: A T
authors.initials: AT
authors.lastname: Matveev
authors.forename: J
authors.initials: J
authors.lastname: Strempfer
authors.forename: H-U
authors.initials: HU
authors.lastname: Habermeier
authors.forename: D V
authors.initials: DV
authors.lastname: Shantsev
authors.forename: Y M
authors.initials: YM
authors.lastname: Galperin
authors.forename: T H
authors.initials: TH
authors.lastname: Johansen