PROPERTIES OF SUPERCONDUCTOR-FERROMAGNET BILAYERS - YBA2CUO3-FE AND YBA2CUO3-PERMALLOY

The superconducting and magnetic properties of thin films of ferromagn etic iron and Permalloy deposited on thin films of YBa2Cu3O7-delta hav e been investigated. The ferromagnetic films were 50-300 angstrom thic k, while the superconducting films were 1000-2000 angstrom thick, The superconducting properties of the films were not affected by the prese nce of the magnetic layers, but marked changes in the ferromagnetic re sonance spectra of the iron and Permalloy films were observed, includi ng the appearance of a large and temperature-dependent magnetic anisot ropy. These effects are attributed to the development of a spin-glass- like phase at the superconductor-ferromagnet interface which is couple d to the bulk of the ferromagnetic.