S 68 Smolyak, B. M. Retardation of the Magnetic Relaxation in High-Temperature Superconductors Near a Ferromagnet / B. M. Smolyak, G. V. Ermakov, M. S. Zakharov // Journal of Superconductivity and Novel Magnetism. - 2011. - Vol.24, №1-2. - С. 325-329 Рубрики: ФИЗИКА Кл.слова (ненормированные): HIGH-T C SUPERCONDUCTORS -- TRAPPED FLUX -- MAGNETIC RELAXATION Аннотация: The creep of a magnetic flux trapped in a bulk high-temperature superconductor has been studied. It has been found that the magnetic relaxation is retarded when the superconductor is placed near a ferromagnet. The value of the retardation effect depends on the sequence of magnetization and the approach of the superconductor to a ferromagnet. The magnetic relaxation is fully suppressed when a superconducting sample first is magnetized and then is brought close to a ferromagnet. An interpretation of this effect has been discussed. Being magnetized, a ferromagnet produces its own magnetic field. While penetrating into a disk sample through its planes, the ferromagnet field induces screening currents, which circulate oppositely to the current that arises upon trapping of the magnetic flux. As a result, the stability of the magnetic structure is sharply improved since opposite driving forces can act on different sections of the vortices |