Europhys. Lett.
Volume 63, Number 1, July 2003
Page(s) 118 - 124
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 June 2003
DOI: 10.1209/epl/i2003-00486-2
Europhys. Lett., 63 (1) , pp. 118-124 (2003)

Flux pinning by regular nanostructures in $\chem{Nb}$ thin films: Magnetic vs. structural effects

M. I. Montero1, J. J. Åkerman2, A. Varilci3 and I. K. Schuller1

1  Physics Department, University of California San Diego - La Jolla, CA 92093, USA
2  Motorola Labs - 7700 S. River Parkway, Tempe, AZ 85284, USA
3  Department of Physics, Faculty of Arts and Sciences, Karadeniz Technical University 61080 Trabzon, Turkey

(Received 11 June 2002; accepted in final form 17 April 2003)

Periodic pinning effects in indented $\chem{Nb}$ films and $\chem{Nb}$ films with rectangular arrays of submicrometric $\chem{Ni}$ dots were studied. The indented samples consisted of $\chem{Nb}$ film deposited on top of $\chem{Si}$ substrates patterned with rectangular arrays of nanoholes. Pinning effects can be observed in the evolution of resistivity and critical current with the applied magnetic field, showing the same qualitative behavior, for both types of samples. The main difference between them is that the matching effects are more pronounced in the samples with magnetic dots. The analysis and comparison of these results allows determining the pinning as due to superconductivity suppression around the nanostructures (indentations or dots) due to a thickness reduction. For the samples with magnetic dots, this suppression of superconductivity is reinforced by the magnetic proximity effect.

74.25.Qt - Vortex lattices, flux pinning, flux creep.
74.25.Sv - Critical currents.

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