Soft Magnetic Properties of Fe-Ni-Nb Alloy Films
The relation between the soft magnetic properties and local anisotropy fluctuation measured by the dynamic differential susceptibility method in Fe-Ni-Nb alloy films was clarified and discussed in comparison with Fe-Si-Al alloy films. Fe-Ni-Nb alloy films with excellent soft magnetic properties, 5 MHz values of ¿eff = 6500 for 1000 Å thick films were obtained. For Fe-Si-Al alloy films, the magnitude of ¿eff = 6500 is proportional to 1/S2 (where S is a structure constant) and independent of the value of Hk, while for Fe-Ni-Nb alloy films, the value of S is about one-tenth of that in Fe-Si-Al alloy films, and the magnitude of ¿eff 6500 does not depend on S. Rather, this magnitude is dependent on the value of Hk, and is almost equal to 4¿Ms/Hk, obtained from a rotational magnetization model in a uniaxial single-domain particle.
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.
Susceptibility and Magnetization Ripple in Polycrystalline Magnetic Films
The magnitudes of the magnetic susceptibility components χi and χt of a uniaxial magnetic film, measured parallel to and perpendicular to a hard direction applied field, respectively, are determined by the magnetization‐ripple distribution. They can be shown theoretically to be related directly to one another only if the longitudinal magnetostatic interactions in the ripple are negligible. Experimental results are presented to show that they are related over a rather wide range of applied field.