COLLAPSE OF THE MAGNETIC-MOMENT IN A HARD SUPERCONDUCTOR UNDER THE ACTION OF A TRANSVERSE AC MAGNETIC-FIELD

The suppression of the static magnetic moment M of a superconducting p late by an alternating magnetic field applied perpendicularly to a dc magnetic field has been studied both experimentally and theoretically. Complete disappearance of the hysteresis of the magnetization curve i n YBCO melt-textured samples was observed. Nonmonotonous behavior of M with the increase of the ac magnetic field amplitude was found. The d ynamics of the collapse of the magnetic moment was studied in the puls e regime of the transverse field. The experimental results indicate ho mogeneity of the static magnetic induction in the sample regions where the ac field penetrates. The data obtained are interpreted within the framework of a two-liquid hydrodynamic model. (C) 1997 Elsevier Scien ce B.V.