FLUX-FLOP IN HIGH-TEMPERATURE SUPERCONDUCTING CRYSTALS WITH COLUMNAR DEFECTS

Measurements of magnetization curves of Y-Ba-Cu-0 crystals with column ar defects reveal pronounced peaks around H=0 for applied fields not p arallel to the defect direction. The magnitude and direction of the re manent magnetization are independent of the direction of the applied f ield for a large range of angles. We show that the unidirectional char acter of the defects induces, in the low field limit, a flux-flop from a direction determined by the field to the defect direction. Implicat ions to planar pinning are discussed.