Vortex activation energy in the AC magnetic response of superconducting YBa2Cu3O7 thin films with complex pinning structures

I. Ivan, A. M. Ionescu, D. Miu, Paolo Mele, L. Miu

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The vortex activation energy U AC in the AC magnetic response of superconductors exhibits a logarithmic variation with the screening current density J (regardless of the pinning structure details), and takes surprisingly high values in the vicinity of the DC irreversibility line, especially at low external DC magnetic fields, as often reported. This is essentially different from the behaviour of the vortex-creep activation energy at long relaxation time scales in DC magnetic measurements, and is not completely understood. We investigated the DC relaxation and the AC response for YBa2Cu3O7 films containing nanorods and nanoparticles, with the DC and AC fields oriented perpendicular to the film surface. It is shown that the large U AC values in the vicinity of the DC irreversibility line, where the critical-state-related AC signal occurs, are generated by a non-diffusive vortex motion during the AC cycle, with the mean vortex hopping length longer than the average distance between the pinning centres. In these conditions, the smearing of the vortex pinning potential by thermally induced vortex fluctuations is weak, and U AC mainly results from the strong influence of the pinning-enhanced viscous drag on the vortex hopping process. The logarithmic U AC(J) dependence is consistent with a high U AC.

Original languageEnglish
Article number095013
JournalSuperconductor Science and Technology
Volume29
Issue number9
DOIs
Publication statusPublished - 2016 Aug 8
Externally publishedYes

Fingerprint

Superconducting films
alternating current
Vortex flow
Activation energy
vortices
activation energy
thin films
direct current
Magnetic variables measurement
barium copper yttrium oxide
Nanorods
Relaxation time
viscous drag
Superconducting materials
Drag
Screening
Creep
Current density
Magnetic fields
Nanoparticles

Keywords

  • AC magnetic response
  • DC magnetization relaxation
  • non-diffusive vortex motion
  • superconducting thin films
  • vortex activation energy

ASJC Scopus subject areas

  • Ceramics and Composites
  • Condensed Matter Physics
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

Cite this

Vortex activation energy in the AC magnetic response of superconducting YBa2Cu3O7 thin films with complex pinning structures. / Ivan, I.; Ionescu, A. M.; Miu, D.; Mele, Paolo; Miu, L.

In: Superconductor Science and Technology, Vol. 29, No. 9, 095013, 08.08.2016.

Research output: Contribution to journalArticle

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