Alternating current permeability of defect-free type-II superconductors
A theoretical and experimental study is presented of ac losses in the mixed state of type-II superconductors when viscous damping dominates flux line motion. The theory describes the ac response of a cylindrical superconductor in the mixed state in a dc magnetic field H and a superposed parallel ac field of arbitrary frequency. The complex ac permeability is found to be related to the flux-flow resistivity rho/sub f/(B), the differential permeability ..mu..' (B) = dB/dH, the frequency, and the sample radius. Measurements were made of the ac permeability in the frequency range 45--1000 Hz of two NbTa alloys which were prepared to minimize bulk-pinning and surface losses. Values of rho/sub f/(B) and ..mu..' (B) derived from the measurements agree qualitatively with the model, but rho/sub f/(B) shows a weak frequency dependence that may arise from the presence of remnant nonviscous losses. (AIP)
- Research Organization:
- Ames Laboratory--ERDA and Department of Physics, Iowa State University, Ames, Iowa 50010
- OSTI ID:
- 7359072
- Journal Information:
- Phys. Rev., B; (United States), Journal Name: Phys. Rev., B; (United States) Vol. 14:5; ISSN PLRBA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ELECTRICAL PROPERTIES
MAGNETIC FLUX
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
NIOBIUM ALLOYS
NIOBIUM BASE ALLOYS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
TANTALUM ALLOYS
TANTALUM BASE ALLOYS
TYPE-II SUPERCONDUCTORS