Flux motion in the self-organized critical state of type-II superconductors

摘要

A model based on the concept of self-organized criticality (SOC) is proposed to describe the nonequilibrium flux dynamics of type-II superconductors. The nonlogarithmic magnetic relaxation of high-(Tc) superconductors is argued as an indication of the SOC. The magnetic relaxation of single crystals of YBa(sub 2)Cu(sub 3)O(sub 7-(delta)), Bi(sub 2)Sr(sub 2)CaCu(sub 2)O(sub x) as well as Nb is studied systematically. Relevance to models of the classical Anderson-Kim flux creep, thermally activated flux flow (TAFF), collective creep and vortex-glass is discussed.