Scaling laws for the critical current density of NbN films in high magnetic fields

Author

Hampshire, D.P. ; Gray, K.E. ; Kampwirth, R.T.

Author_Institution

Dept. of Phys., Durham Univ., UK

Volume

3

Issue

1

fYear

1993

fDate

3/1/1993 12:00:00 AM

Firstpage

1246

Lastpage

1252

Abstract

The authors have measured the critical current density (J/sub c/) of two NbN films (500-AA and 1550-AA thick) as a function of temperature in magnetic fields up to 25 T using transport measurements. In both films, the functional form of the volume pinning force F/sub p/ obeys the Fietz-Webb scaling law throughout the entire magnetic field and temperature range. Values of J/sub c/ derived from DC magnetization data using Bean´s model show qualitative agreement with the transport measurements throughout the superconducting phase. Despite the marked granularity in the microstructure of these films, the results are interpreted as evidence that a flux pinning mechanism determines the transport current density in NbN films in high magnetic fields.<>

Keywords

critical current density (superconductivity); crystal microstructure; flux pinning; magnetisation; niobium compounds; superconducting thin films; type II superconductors; 1500 AA; 500 AA; Bean´s model; DC magnetization data; Fietz-Webb scaling law; NbN; critical current density; films; flux pinning; granularity; microstructure; superconductor; volume pinning force; Bean model; Critical current density; Current measurement; Density measurement; Magnetic field measurement; Magnetic films; Magnetization; Superconducting films; Temperature distribution; Thickness measurement;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.233398

Filename

233398