Critical current and vortex dynamics in single crystals of Ca(Fe1−xCox)2As2

We investigate the critical current density and vortex dynamics in single crystals of Ca(Fe1−xCox)2As2 (x=0.051, 0.056, 0.065, and 0.073). The samples exhibit different critical temperatures and superconducting phase fractions. We show that in contrast to their Ba-based counterpart, the crystals do...

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Hauptverfasser: Pramanik, Ashim (VerfasserIn) , Harnagea, L. (VerfasserIn) , Singh, S. (VerfasserIn) , Aswartham, S. (VerfasserIn) , Behr, G. (VerfasserIn) , Wurmehl, S. (VerfasserIn) , Hess, C. (VerfasserIn) , Klingeler, Rüdiger (VerfasserIn) , Büchner, B. (VerfasserIn)
Dokumenttyp: Article (Journal)
Sprache:Englisch
Veröffentlicht: 2 July 2010
In: Physical review. B, Condensed matter and materials physics
Year: 2010, Jahrgang: 82, Pages: 1-7
ISSN:1550-235X
DOI:10.1103/PhysRevB.82.014503
Online-Zugang:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1103/PhysRevB.82.014503
Verlag, lizenzpflichtig, Volltext: https://link.aps.org/doi/10.1103/PhysRevB.82.014503
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Verfasserangaben:A.K. Pramanik, L. Harnagea, S. Singh, S. Aswartham, G. Behr, S. Wurmehl, C. Hess, R. Klingeler, and B. Büchner
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Zusammenfassung:We investigate the critical current density and vortex dynamics in single crystals of Ca(Fe1−xCox)2As2 (x=0.051, 0.056, 0.065, and 0.073). The samples exhibit different critical temperatures and superconducting phase fractions. We show that in contrast to their Ba-based counterpart, the crystals do not exhibit a second peak in the field dependence of magnetization. The calculated composition-dependent critical current density (JC) increases initially with Co doping, maximizing at x=0.065 and then decreases. This variation in JC does not follow the superconducting phase-transition temperature in this series. The calculated JC shows strong temperature dependence, decreasing rapidly upon heating. Magnetic relaxation measurements imply a nonlogarithmic dependence on time. We find that the relaxation rate is large, reflecting weak characteristic pinning energy. The analysis of temperature- and field-dependent magnetic relaxation data suggests that vortex dynamics in these compounds is consistent with plastic creeping rather than the collective creep model, unlike other 122 pnictide superconductors. This difference may cause the absence of the second peak in the field-dependent magnetization of Ca(Fe1−xCox)2As2.
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Beschreibung:Online Resource
ISSN:1550-235X
DOI:10.1103/PhysRevB.82.014503