Microwave response of thin niobium films under perpendicular static magnetic fields

D. Janjušević, M. S. Grbić, M. Požek, A. Dulčić, D. Paar, B. Nebendahl, and T. Wagner
Phys. Rev. B 74, 104501 – Published 1 September 2006

Abstract

The microwave response of high quality niobium films in a perpendicular static magnetic field has been investigated. The complex frequency shift was measured 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. This model is found to yield consistent results for the coherence lengths in high-κ superconducting samples, and can be used with high-temperature superconductors even at temperatures much below Tc. It is shown that for samples with high values of depinning frequency, one should measure both components of the complex frequency shift in order to determine the flow resistivity. The thick Nb film (160nm) has low resistivity at 10K, comparable to the best single crystals, and low κ value. In contrast, the thinnest (10nm) film has κ9.5 and exhibits a high depinning frequency (20GHz). The upper critical field determined from microwave measurements is related to the radius of nonoverlaping vortices, and appears to be larger than the one determined by the transition to the normal state.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 7 February 2006

DOI:https://doi.org/10.1103/PhysRevB.74.104501

©2006 American Physical Society

Authors & Affiliations

D. Janjušević, M. S. Grbić, M. Požek*, A. Dulčić, and D. Paar

  • Department of Physics, Faculty of Science, University of Zagreb, P. O. Box 331, HR-10002 Zagreb, Croatia

B. Nebendahl

  • Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart, Germany

T. Wagner

  • Max-Planck-Institute for Metals Research, Heisenbergstrasse 3, D-70156 Stuttgart, Germany

  • *Electronic address: mpozek@phy.hr
  • Present address: Agilent Technologies R&D and Marketing GmbH & Co. KG, Herrenberger Strasse 130, D-71034 Böblingen, Germany.

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 74, Iss. 10 — 1 September 2006

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×