Magnetic relaxation in hard type-II superconductors
Department of Condensed Matter Physics and Material Sciences
Tata Institute of Fundamental Research - Colaba, Mumbai, 400 005 India
Accepted: 7 December 1999
Magnetic relaxation in a type-II superconductor is simulated for a range of temperatures T in a simple model of the 2D Josephson junction array (JJA) with finite screening. The high-T phase, that is characterised by a single time scale , crosses over to an intermediate phase at a lower temperature Tcr wherein a second time scale emerges. The relaxation in the time window set by follows a power law which is attributed to self-organization of the magnetic flux during relaxation. Consequently, for , a transition from super-critical (current density ) to sub-critical () state separated by an intermediate state with frozen dynamics is observed. Both and diverge at , marking the transition into a state with true persistent current.
PACS: 74.60.Ge – Flux pinning, flux creep, and flux-line lattice dynamics / 74.60.Jg – Critical currents
© EDP Sciences, 2000