Effect of Local Anisotropy Fluctuation on the Permeability of Multilayered Co-Zr-Mo-Ni Amorphous Films
To evaluate the magnetic inhomogeneities normally represented as magnetic skew and ripple, a systematic experimental investigation was carried out using the dynamic differential susceptibility measurement proposed by H. Hoffmann for multilayered CO79Zr10Mo9Ni2 amorphous films. The influence of the local magnetic anisotropy on the effective permeability μeff of the films is broadly discussed in connection with the magnetic skew and ripple. The magnitude of the μeff in low frequency regions less than 1 MHz is strongly dependent on the degree of the long period fluctuation of the local magnetization direction (skew) and the magnitude of the anisotropy field. To realize excellent soft magnetic properties in films at high frequencies (10 MHz), it is suggested that the alleviation of magnetic inhomogeneities due to the short-period fluctuation of the local magnetization direction is important.
The Effective Field and the Differential Susceptibility in Ferromagnetic Films
A theory of the differential susceptibility is given for two-dimensional ferromagnetic samples. The susceptibility depends on the intrinsic demagnetizing field which is caused by the magnetization inhomogeneities. The susceptibility is related to the mean “effective field” as well as to the magnetization fluctuation. Its measurement can be used to determine quantitatively these properties which are related to the structure constant, S. The latter results from the inhomogeneity of the anisotropy. 
 
 
 
Es wird eine Theorie der differentiellen Suszeptibilitat in zweidimensionalen ferromagnetischen Proben hergeleitet, um damit die Anwendungsmoglichkeiten quantitativer mikromagnetischer Berechnungen aufzuzeigen. Die Suszeptibilitat in schwachen auseren Feldern wird wesentlich mitbestimmt durch das von Probeninhomogenitaten verursachte innere entmagnetisierende Feld. Die Suszeptibilitat ist mit dem „Effektivfeld” und den Schwankungen der Magnetisierungsrichtungen eng verknupft und kann zur Ermittlung beider Grosen herangezogen werden. Beide werden durch die Strukturkonstante S bestimmt, in welcher die inhomogenen Energieanteile der Probe zum Ausdruck kommen.
Stray fields in thin magnetic films
From the second variation of the integral of all free energies in thin magnetic films, an effective field h_{eff}(\alpha) is deduced, which for real polycrystalline films is analogous to the Stoner-Wohlfarth field h(\alpha) of ideal single-domain films. The effective field is composed of the single-domain field, two different stray fields, and a field caused by local anisotropies. The h_{eff}(\alpha) varies from point to point. As in the single-domain theory, h_{eff}(\alpha) > 0 means that the magnetization direction over the entire film is stable; in regions with h_{eff}(\alpha) = 0 , the local magnetization becomes unstable and turns by a very small angle to another stable state. After that, the domain structure is blocked by the intrinsic stray field. The blocking condition, which is the external single-domain field at which blocking occurs, is calculated as a function of film structure. The critical curve for stray-field blocking shows that the critical Stoner-Wohlfarth curve of the single-domain theory must not be used in discussing experiments on real polycrystalline films.