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.
Stress and Magnetic Anisotropy in Thin Permalloy Films
A UNIAXIAL magnetic anisotropy is observed in thin nickel–iron films which have been deposited, in the presence of a uniform magnetic field, on to a heated glass substrate supported in vacuum. Macdonald1 and Finegan and Hoffman2 have reported that both nickel and iron films can be in a state of anisotropic stress. Nickel, for example, can contain an anisotropic planar compression of about 5 × 108 dynes/ cm.2. Such an anisotropic stress, if present in the nickel–iron films, could contribute to the magnetic anisotropy both directly through the magnetostriction, and indirectly through stress-induced iron-pair directional ordering, as suggested by Zener3. Several authors4–6 have used such stresses in explaining, at least in part, the magnetic anisotropy of thin nickel–iron films. However, no direction observations of the stress in evaporated nickel–iron films have been reported.