抄録
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.
| 元の言語 | English |
|---|---|
| 記事番号 | 095013 |
| ジャーナル | Superconductor Science and Technology |
| 巻 | 29 |
| 発行部数 | 9 |
| DOI | |
| 出版物ステータス | Published - 2016 8 8 |
| 外部発表 | Yes |
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ASJC Scopus subject areas
- Ceramics and Composites
- Condensed Matter Physics
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry
これを引用
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.
：: Superconductor Science and Technology, 巻 29, 番号 9, 095013, 08.08.2016.研究成果: Article
}
TY - JOUR
T1 - Vortex activation energy in the AC magnetic response of superconducting YBa2Cu3O7 thin films with complex pinning structures
AU - Ivan, I.
AU - Ionescu, A. M.
AU - Miu, D.
AU - Mele, Paolo
AU - Miu, L.
PY - 2016/8/8
Y1 - 2016/8/8
N2 - 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.
AB - 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.
KW - AC magnetic response
KW - DC magnetization relaxation
KW - non-diffusive vortex motion
KW - superconducting thin films
KW - vortex activation energy
UR - http://www.scopus.com/inward/record.url?scp=84985931125&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84985931125&partnerID=8YFLogxK
U2 - 10.1088/0953-2048/29/9/095013
DO - 10.1088/0953-2048/29/9/095013
M3 - Article
AN - SCOPUS:84985931125
VL - 29
JO - Superconductor Science and Technology
JF - Superconductor Science and Technology
SN - 0953-2048
IS - 9
M1 - 095013
ER -