FLUX-CREEP MECHANISM STUDIED IN EXTENDED WINDOWS FOR THE HGBA2CA2CU3O-GAMMA SUPERCONDUCTOR

Flux-creep mechanisms are examined by the current density J dependence of the effective barriers U(J), which were determined to be U(J) alph a J(-mu) by three independent measurements i.e. AC susceptibility (ACS ), magnetic relaxation (M-t) and hysteresis loop (M-H) for polycrystal line HgBa2Ca2Cu3Oy. It is found that, as J is increased, the U(J) of M -N decreases monotonically and gradually crosses over from mu = 0.43, which connects smoothly with the ACS one with J approximate to 10(2) A /cm(2), to the one with mu = 1.03, which just overlaps with the M-t on e with J approximate to 10(6) A/cm(2). This result demonstrates the co nsistency of the data of the three methods and is considered to be evi dence of a crossover between the CDW type and large bundle creep in th e vortex-glass phase or collective-creep theories.