Time scales of the flux creep in superconductors

Journal Article · Wed Sep 01 00:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.6477· OSTI ID:6213793

Gurevich, A ^[1]; Kuepfer, H ^[2]

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1. Applied Superconductivity Center, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
2. Kernforschungszentrum Karlsruhe, Institut fuer Technische Physik, Postfach 3640, Karlsruhe, D-7500 (Germany)

We have studied both theoretically and experimentally flux-creep dynamics in superconductors. A theoretical analysis of nonlinear flux diffusion shows that the relaxation of the electric field proves to be similar for different models of thermally activated flux creep, whereas the long-time decay of the magnetic moment [ital M]([ital t]) can be essentially model dependent. A proposed scaling analysis indicates that the short-time decay of [ital M]([ital t]) in the subcritical region [ital j][lt][ital j][sub [ital c]] is universal and consists of two stages. The initial nonlogarithmic stage is due to a transient redistribution of magnetic flux over the sample cross section, the duration of this stage [tau][sub 0] being entirely determined by macroscopic quantities, such as sample sizes, flux creep rate [ital M][sub 1]([ital T],[ital B])=[ital dM]/[ital d] ln[ital t], and magnetic ramp rate [ital [dot B]][sub [ital e]]=[ital dB]/[ital dt]. The second stage corresponds to the approximately logarithmic relaxation [ital M]([ital t])=[ital M][sub [ital c]][minus][ital M][sub 1]ln([ital t]/[ital t][sub 0]), with [ital t][sub 0] being a macroscopic time constant that also depends on sample sizes, [ital M][sub 1]([ital T],[ital B]), and the voltage criterion [ital E][sub [ital c]] at which the critical current density [ital j][sub [ital c]] is defined.

• OSTI ID: 6213793
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 48:9; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
RELAXATION
COPPER OXIDES
TYPE-II SUPERCONDUCTORS
MAGNETIC FLUX
YTTRIUM OXIDES
HIGH-TC SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SUPERCONDUCTORS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
665411* - Basic Superconductivity Studies- (1992-)