Electrical transport and pinning properties of Nb thin films patterned with focused ion beam-milled washboard nanostructures
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Дата
2012-11-22
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New J. Phys.
Анотація
A careful analysis of the magneto-transport properties of epitaxial
nanostructured Nb thin films in the normal and the mixed state is performed. The
nanopatterns were prepared by focused ion beam (FIB) milling. They provide a
washboard-like pinning potential landscape for vortices in the mixed state and
simultaneously cause a resistivity anisotropy in the normal state. Two matching
magnetic fields for the vortex lattice with the underlying nanostructures have
been observed. By applying these fields, the most likely pinning sites along
which the flux lines move through the samples have been selected. By this,
either the background isotropic pinning of the pristine film or the enhanced
isotropic pinning originating from the nanoprocessing have been probed. Via
an Arrhenius analysis of the resistivity data the pinning activation energies for
three vortex lattice parameters have been quantified. The changes in the electrical
transport and the pinning properties have been correlated with the results of the
microstructural and topographical characterization of the FIB-patterned samples.
Accordingly, along with the surface processing, FIB milling has been found to
alter the material composition and the degree of disorder in as-grown films. The
obtained results provide further insight into the pinning mechanisms at work in
FIB-nanopatterned superconductors, e.g. for fluxonic applications.
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Research Subject Categories::NATURAL SCIENCES
Бібліографічний опис
New Journal of Physics 14 (2012) 113027 (27pp)