Relaxation of persistent current and the energy barrier {ital U}{sub eff}({ital J}) close to {ital T}{sub {ital c}} in a grain-aligned YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} ring
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G2J1 (Canada)
- Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 1-16-25 Shibaura, Minato-ku, Tokyo 105 (Japan)
- Department of Physics, University of Lethbridge, Lethbridge, Alberta, T1K 3M4 (Canada)
- Department of Electrical Engineering, University of Alberta, Edmonton, Alberta, T6G 2G7 (Canada)
At fixed value of time, {ital U}{sub eff}({ital J}) calculated from the Beasley, Labusch, and Webb [Phys. Rev. 181, 682 (1969)] rate equation for thermally activated motion of flux, is current independent up to about 0.6--0.7{ital J}{sub {ital c}} and at higher currents it drops linearly with increasing current. {ital U}{sub eff}({ital J},{ital T}) for a steady-state logarithmic relaxation provides a high-temperature extension of {ital U}{sub eff}({ital J}) measured at low temperatures in grain-aligned YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} with Maley`s method [Phys. Rev. B 48, 13 992 (1993)], suggesting a gradual conversion of the flux-creep process from a vortex-glass or collective flux creep at low temperatures to Anderson single-barrier vortex creep at high temperatures.
- OSTI ID:
- 44547
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 17 Vol. 51; ISSN 0163-1829; ISSN PRBMDO
- Country of Publication:
- United States
- Language:
- English
Similar Records
Flux-creep studies of vortex pinning in an aligned YBa sub 2 Cu sub 3 O sub 7 minus. delta. superconductor with oxygen deficiencies. delta. le 0. 2
[ital U]-[ital j] relationship in type-II superconductors