Vortex lattice channeling effects in Nb films induced by anisotropic arrays of mesoscopic pinning centers

M. Velez
Depto. Física, F. Ciencias, Universidad de Oviedo, Av. Calvo Sotelo s/n, 33007 Oviedo, Spain

D. Jaque
Depto. Física de Materiales, Ciencias Físicas, Universidad Complutense, Av. Complutense s/n, 28040 Madrid, Spain

J. I. Martín
Depto. Física, F. Ciencias, Universidad de Oviedo, Av. Calvo Sotelo s/n, 33007 Oviedo, Spain

M. I. Montero and Ivan K. Schuller
Physics Department, University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093-0319

J. L. Vicent
Depto. Física de Materiales, Ciencias Físicas, Universidad Complutense, Av. Complutense s/n, 28040 Madrid, Spain

Received 14 September 2001; published 14 February 2002

Rectangular arrays of Ni dots with small interdot separation have been fabricated in superconducting Nb films. The geometry of these rectangular arrays defines deep pinning potential channels. Two effects have been observed. (i) When the vortices move perpendicular to the channels (i.e., along the long side of the rectangular array) an enhancement of the background pinning is observed, as predicted by theoretical models. This enhancement occurs for all magnetic fields. (ii) A new anisotropic matching effect, which has not been theoretically predicted, has been measured. The position of the matching fields depends on the direction of the vortex flow. When the vortices move parallel to the potential channels (i.e., along the short side of the rectangular array) the vortex lattice matches the rectangular array, but when they move along the long side of the rectangular array only a triangular lattice is observed.
ROSSANA HERNANDEZ
C.I 19234948
ESTADO SOLIDO
http://prb.aps.org/abstract/PRB/v65/i10/e104511

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