Suppression of the magnetic moment under the action of a transverse magnetic held in hard superconductors

The suppression of the static magnetic moment M of a superconducting plate in the critical state by a sweeping magnetic field (h) over right arrow(t), applied perpendicularly to a dc magnetic field H, has been studies experim entally and theoretically. For every quarter-period of a sweeping field h(T ) of changing polarity with an amplitude h(0), a noticeable decrease of M c an be observed both for the paramagnetic and diamagnetic initial states eve n for small h(0) compared to H. Numerical simulations within the framework of two existing theoretical approaches have been performed in order to stud y the evolution of the distribution of the magnetic induction and the suppr ession of the magnetic moment. It turns out that the Clem-Perez-Gonzalez do uble critical-state model describes this process qualitatively well in the first quarter-period for relatively high values of h(0). A significant disa greement with the experimental data is observed for small values of the tra nsverse magnetic held. On the other hand, the two-velocity hydrodynamic mod el provides an adequate explanation of the main features of the suppression of M for both paramagnetic and diamagnetic states and any values of h(0).