Naslov
Mixed state conductivity of thin niobium films in perpendicular magnetic fields

Autori
Požek, Miroslav ; Grbić, Mihael Srđan ; Janjušević, Dragan ; Dulčić, Antonije ; Paar, Dalibor ; Wagner, Thomas

Izvornik
Physica C (0921-4534) 460-462 (2007), 2; 1291-1292

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Nb thin films; upper critical fields; microwave response

Sažetak
Microwave complex frequency shift has been measured for high quality niobium films in perpendicular static magnetic fields up to the upper critical fields. The data have been analyzed by the effective conductivity model for the type-II superconductors in the mixed state. The depinning frequencies and the upper critical fields have been determined from the analysis. The film of thickness 10 nm has $\kappa \approx 9.5$ and depinning frequency $\approx 20$ GHz. It can serve as a model system for high-$\kappa$ superconductors. The upper critical fields were determined by the flow resistivity in low fields and by the crossover to the normal state. The former method gives slightly higher upper critical field values, reflecting the Ginzburg-Landau coherence length of nonoverlaping vortices.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

Napomena
Proceedings of the 8th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors - M2S-HTSC VIII, Dresden, Germany, 9-14 July 2006, Edited by B. Büchner and J. Fink

POVEZANOST RADA