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 Effect of Strain on the Susceptibility of Polycrystalline Ni–Fe Films
Various ripple effects in uniaxial polycrystalline magnetic films have been related by several authors to an effective single‐grain crystalline anisotropy constant K. If either an isotropic planar stress σ or a uniaxial strain e33 is applied to such a film, the ripple properties are altered. We develop a simple model which includes the effects of such stresses and strains. We thereby evaluate K as an effective crystalline anisotropy given by K=[(K1+Bse33+¼Bσσ)2+(7/16)(Bσσ)2],1/2 where K1 is the fourth order magneto‐crystalline anisotropy constant, and B8 and Bσ are appropriate magnetoelastic coupling constants. A convenient ripple parameter is (HP‐HK), where HK is the uniaxial anisotropy field of the film and HP is the field in the hard direction at which the in‐phase component of the transverse differential susceptibility is a maximum. Measurements of (HP‐HK) vs e33 taken on electroplated cylindrical Ni–Fe films varying in thickness from 3000 A to a 10,000 A are presented. While the results are qualitati...
Berechnung des Magnetisierungs-„Ripple“ in ferromagnetischen dünnen Schichten
By means of straight forward analysis a complete calculation is given of magnetization ripple in polycrystalline ferromagnetic films. Wavelenghts and practical relations for ripple amplitude, length of coherence, and angle fluctuation are derived (which were so far only rather incompletely available from a very rough model of the ripple, given previously by the author). The dependence of ripple wavelength (λ0) on average crystallite sizea reaches a plateau at a definite critical valuea=ag∶λ0≈4a foraag, as has been found most recently byBaltz andDoyle.