Time relaxation of persistent currents in YBa2Cu3O7−x crystals with columnar defects

L. CIVALE, G. PASQUINIB, P. LEVY, G. NIEVA, 1, D. CASA AND H. LANZA

PHYSICA C - SUPERCONDUTIVITY

ELSEVIER SCIENCE BV

Lugar: New York; Año: 1996 vol. 263 p. 389 - 395

0921-4534

Abstract We have measured the persistent currents and their time relaxation in YBa2Cu3O7−x single crystals with correlated disorder introduced by irradiation with high-energy heavy-ions. For vortex density lower than the defect density, and for applied fields either parallel or nonparallel to the columnar defects, we find clear evidence of a pinning-crossover between a regime of strong individual pinning at low temperatures and a regime of weaker collective pinning at high temperatures. We explore the vortex dynamics above and below this crossover.