Super-Fast Vortex Creep in YBa2Cu3O7-delta Crystals with Columnar Defects: Evidence for Variable Range Vortex Hopping

        We observe an enormous peak in the vortex creep rate of YBa2Cu3O7-delta crystals with columnar defects. The peak articulates at the crossover from the regime where vortices are well localized on columnar pins to a regime where vortex-vortex interactions dominate, and it is most prominent (nearly 12%) at low fields, near T ~ 40K. Near this crossover, the current dependent creep activation energy U(J) shows distinct and unusual behavior (pinch). On the high-J side of the pinch, the glassy exponent u ~ 1/3 and large creep rate are characteristic of variable range vortex hopping.

By: J. R. Thompson (Oak Ridge Nat'l. Lab.), L. Krusin-Elbaum, L. Civale (CNEA, Argentina), G. Blatter (ETH, Switz.) and C. Feild

Published in: RC20482 in 1996

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