Transport relaxation measurements and glassy state effects in superconducting MgB2
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Dosyalar
Tarih
2008
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier B.V. All
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Time dependent effects in superconducting MgB2 have been studied systematically for the first time by transport relaxation measurements (V-t curves) as a function of transport current (I), temperature (T) and external magnetic field (H). At very low dissipation levels (below similar to 1 mu V), it was observed that the sample voltage grows up smoothly in time by exhibiting the details of initial stage of relaxation process. At high dissipation levels, steady state corresponding to constant flow rate is maintained within a very short time and monitoring of details of flux dynamic evolving along sample becomes difficult on long time scales. Another interesting behavior is the appearance of voltage peak when the transport current was reduced to a finite value. After peak, it was observed that the sample voltage relaxes smoothly by leveling off within a very short time. The evolution of V-t curves suggests that formation of resistive flow channels along sample develops easily, which is quite similar to that of obtained for the superconducting ceramic samples whose grain boundaries are improved. Time dependent effects were also observed in magnetovoltage measurements (V-H curves) as the field sweep rate (dH/dt) varies. The observations were interpreted mainly in terms of flux trapping in grains. (C) 2008 Elsevier B.V. All rights reserved.
Açıklama
20th International Symposium on Superconductivity -- NOV 05-07, 2007 -- Tsukuba, JAPAN
Anahtar Kelimeler
Flux Pinning, Magnetovoltage, Type-II Superconductors
Kaynak
Physica C-Superconductivity And Its Applications
WoS Q Değeri
Q4
Scopus Q Değeri
Q2
Cilt
468
Sayı
15-20
