MAGNETIC-RELAXATION IN AN ISOTROPIC EXTREME TYPE-II SUPERCONDUCTOR
1991 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 43, 2735-2741 p.Article in journal (Refereed) Published
The time dependence of the zero-field-cooled and thermoremanent magnetization of the isotropic extreme type-II superconductor PbMo6S8 has been measured at temperatures 0.7 less-than-or-equal-to T/T(c) less-than-or-equal-to 0.95 and for fields 1 less-than-or-equal-to H less-than-or-equal-to 300 G. The results show that the time dependence of the decay can be divided into three different field regimes: (1) A low-field regime with a closely logarithmic decay and a well-established critical state. The relaxation rate [partial M/partial ln(t)] increases as H-5 for the zero-field-cooled magnetization and as H-2.4 for the thermoremanent magnetization. The reduction in magnetization over 5 decades in time (0.3-3 X 10(4) s) is, at most, a few percent. (2) A crossover-field regime with a change from a logarithmic to a nonlogarithmic decay. (3) A high-field regime where the time dependence of the decay is well described by the expression delta-M approximately [ln(t/tau-0)]-alpha. The reduction in magnetization in the crossover- and high-field regimes is as large as 25-30% in the measured time interval. The results in the high-field regime are interpreted within the theory of collective flux creep. Comparisons are made with the magnetic relaxation found in anisotropic high-T(c) superconductors.
Place, publisher, year, edition, pages
1991. Vol. 43, 2735-2741 p.
Condensed Matter Physics
IdentifiersURN: urn:nbn:se:uu:diva-195548DOI: 10.1103/PhysRevB.43.2735OAI: oai:DiVA.org:uu-195548DiVA: diva2:607938