Vortex pinning and critical currents in nanostructured novel superconductors
| Autor: | Kušević, Ivica, Babić, Emil |
|---|---|
| Přispěvatelé: | Dou, Shi Xue |
| Jazyk: | angličtina |
| Rok vydání: | 2005 |
| Předmět: | |
| Zdroj: | Fizika A Volume 14 Issue 1 Fizika A : a journal of experimental and theoretical physics |
| ISSN: | 1330-0008 1333-9125 |
| Popis: | A systematic analysis of the parameters associated with vortex pinning in novel superconductors containing nano-scale strong isotropic pinning centres (such as U/n processed Bi2223/Ag tapes and nanoparticle added MgB2) has been carried out. Although the systems studied are very different as regards their structures, types of nano-scale defects and vortices, their pinning parameters (irreversibility fields and the fields for the maximum volume pinning force) show distinct common features. In particular, for moderate defect densities nφ, in all these systems the enhancement of the pinning parameters in nanostructured state is approximately linear in nφ over sizable field and temperature windows. Accordingly, these systems exhibit a kind of matching effects with the effective matching field Bφ, correlated with the areal density of defects. The field Bφ forms a natural field scale for the vortex pinning phenomena in such systems. However, at fields far from Bφ, an interplay of different pinning mechanisms sets in. The impact of these results for the future enhancement of the flux pinning and critical currents in nanostructured Bi2223 and MgB2 superconductors is briefly discussed. Predstavljamo sustavnu analizu parametara zapinjanja magnetskih vrtloga u novim supravodičima koji sadrže jake izotropne nanoskopske centre zapinjanja kao što su Bi2223/Ag trake obrađene sa U/n i MgB2 punjen nanočesticama silicija. Iako su ti materijali vrlo različiti u pogledu kristalne strukture, prirode vrtloga i nanoskopskih defekata, njihovi parametri zapinjanja vrtloga (ireverzibilna polja i polja maksimalne volumne sile zapinjanja) pokazuju izrazito slična svojstva. Npr., u tim je materijalima pojačanje zapinjanja vrtloga pri umjerenim gustoćama defekata nφ približno linearno s nφ u širokom području temperatura i magnetskih polja. Ukratko, ti materijali pokazuju učinke usklađivanja s efektivnim poljima usklađivanja Bφ razmjernim nφ. Polje Bφ čini prirodnu ljestvicu polja za zapinjanje vrtloga u takvim sustavima. Medutim, u poljima daleko od Bφ dolazi do miješanja različitih mehanizama zapinjanja vrtloga. Sažeto se razmatra utjecaj ovih saznanja na buduće pojačanje zapinjanja vrtloga u nanostrukturiranim Bi2223 i MgB2 supravodičima. |
| Databáze: | OpenAIRE |
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