J. Wingbermühle, B.K. Kuanr, D. Bürgler, and P. Grünberg

Employing a nonresonant broadband technique, we have measured the complex scattering matrix S-parameters, (Sll and S12) of polycrystal1ine permalloy (Py) from 1 MHz to 20 GHz to estimate resonance as well as off-resonance high frequency losses. Our technique employs a Vector Network Analysator (VNA) Hewlett-Packard model HP8720B sending a phase-locked signal into a coaxial transmission line (50 n), which is terminated by the thin film sample. It is well known that NiO/Py interfaces give rise to an unidirectional anisotropy called exchange anisotropy (Hex). We have used the VNA technique to measure the exchange anisotropy and the field-induced uniaxial anisotropy (Hu) in pinned (NiO/Py) and unpinned Py films.