Influence of crossed fields in structures combining large grain, bulk (RE)BCO superconductors and soft ferromagnetic discs

Bulk (RE)BCO superconductors are able to trap record magnetic fields and can be
used as powerful permanent magnets in various engineering applications such as rotating
machines and magnetic bearings. When such superconducting (SC) “trapped field magnets” are
combined to a ferromagnetic (FM) disc, the total magnetic moment is increased with respect to
that of the superconductor alone. In the present work, we study experimentally the magnetic
behaviour of such hybrid FM/SC structures when they are subjected to cycles of applied field
that are orthogonal to their permanent magnetization, i.e. a “crossed-field” configuration.
Experimental results show that the usual “crossed-field demagnetization” caused by the cycles
of transverse field is strongly reduced in the presence of the ferromagnet.