Observation of vortex distribution in YBCO-QMG samples and YBCO thin films

We have examined vortex distribution of YBa2Cu3O7-delta (YBCO, Y-123) films and YBCO-QMG samples. The vortices were observed by the Bitter method using the decoration of the fine magnetic particles. Observation of vortex distribution was done in the temperature range between 25 and 90 K in the magnetic field range between 0 and 10 mT. We found that vortices of YBCO films and YBCO-QMG samples did not move at 25 K and moved slightly at 75 K, and the interface of the Y2BaCuO5 (Y-211) and Y-123 phases of the YBCO-QMG sample works as pinning center. (C) 2002 Elsevier Science B.V. All rights reserved.