Eur. Phys. J. B 52, 459-463 (2006)
https://doi.org/10.1140/epjb/e2006-00320-9

Critical-state effects on microwave losses in type-II superconductors

CNISM and Dipartimento di Scienze Fisiche ed Astronomiche, Università di Palermo, via Archirafi 36, 90123 Palermo, Italy

Corresponding author: ^a livigni@fisica.unipa.it

Received: 18 April 2006
Revised: 21 June 2006
Published online: 7 August 2006

Abstract

We discuss the microwave energy losses in superconductors in the critical state. The field-induced variations of the surface resistance are determined, in the framework of the Coffey and Clem model, by taking into account the distribution of the vortex magnetic field inside the sample. It is shown that the effects of the critical state cannot generally be disregarded to account for the experimental data. Results obtained in bulk niobium at low temperatures are quantitatively justified.