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The influence of a submicrometre antidot array on the vortex topology and the pinning mechanisms in layered superconductors
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Influence of a submicrometre antidot array on the vortex topology and the pinning mechanisms in layered superconductors
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Upper critical fields and interface transparency in superconductor/ferromagnet bilayers.
No full textHigh-velocity instabilities in the vortex lattice ofNb/Permalloy Bilayers
Get PDFWe have studied the critical current density Jc for onset of vortex motion and the dynamic instability of the
moving vortex lattice at high driving currents in superconducting (S)/ferromagnetic (F) Nb/Ni0.80Fe0.20 bilayers
and in a single Nb film with the same thickness. The samples are all characterized by relatively high values
of the pinning strength. The measured current-voltage characteristics are successfully described in the framework
of the Larkin-Ovchinnikov model, modified in order to take into account the effect of the pinning close
to the instability. We find that Jc is smaller in the S/F bilayers than in the single film and argue that this is due
to the strongly inhomogeneous order parameter in the bilayers. Also, the critical velocity v* for the occurrence
of the instability is found to be significantly larger in the S/F bilayers than in the single S layer. By extracting
the quasiparticle energy relaxation rate from v*, we show that this effect is due to the same inhomogeneous
order parameter and the resulting lower average value of the superconducting gap
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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