Barkhausen effect in stepped motion of a plane domain boundary in gadolinium molybdate

Barkhausen pulses generated in stepped motion of a single plane domain boun dary (PDB) are investigated experimentally in single-crystalline wafers of the extrinsic ferroelastic ferroelectric gadolinium molybdate containing ar tificial pinning centers of the "field inhomogeneity'' type near the edges of the sample. Two scenarios of the evolution of a PDB in interaction with "defects'' are proposed on the basis of analyzing the shape of the pulses i n a linearly increasing field: small changes of the pulse shape in a weak f ield and the generation of wedge domains in a strong field. The proposed me chanism of PDB motion due to the generation of steps near the edge of the s ample and their longitudinal motion provides a means for explaining the exp erimentally observed linear field dependence of the PDB velocity and for de termining the velocity of the steps. (C) 1999 American Institute of Physics . [S1063-7834(99)02202-9].