Frequency dependence of the transverse biased permeability in thin permalloy films

Abstract

The frequency dependence of t.he transverse biased permeability ,u: if ) has been measured up to 250 MHz in thin (0.044 pm) and thick (2.1 pm) unpatterned sputtered permalloy films with uniaxial anisotropy. In these films, the initial permeability along the hard axis can be described by the classical eddy current damping model assuming uniform rotation. For both films, pi at low frequency agrees reasonably well with Hoffman's ripple model assuming appropriate values for the structure factor. In the thin film, pi (f ) is independent of frequency within experimentai error up to at least 250 MHz. However, in the thick film pi(f ) decreases more rapidly with frequency than can be explained by classical eddy currents, when the transverse bias field HB is not very large compared to the net anisotropy field. The value of H, at which &(f ) reaches a maximum amplitude is also found to increase monotonically with increasing frequency, also inconsistent wit.h simple eddy c.urrent predictions, It is suggested that the formation of ripple walls leads to anomalous eddy current losses similar to that observed in bulk materials.

A study on the thickness dependence of static and dynamic magnetic properties of Ni81Fe19 thin films

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“…For many years Permalloy (Py) thin films have received a lot of attention due to its outstanding magnetic properties [1][2][3][4] which includes high permeability, low anisotropy and high saturation magnetization. Such features have enabled several applications as for example, magnetic transducers, magnetorresistive random access memory and soft underlayers in perpendicular magnetic recording [5].…”

Giant magneto-impedance effects in Metglas 2705M

“…The peak location of 6.5 Oe marks the value of H i ϭHϪ4D L M ϷH K , and corresponds to the peak observed in the transverse differential susceptibility. 6,7 The cen- tral peaks, or the inner peaks ͑labeled b and c in Fig. 2͒, as shown in Fig.…”

Frequency-dependent complex permeability in Zr-substituted permalloy thin films

“…Thus, it is possible to tune the resonance frequency, defined as the frequency for which the real part of the susceptibility passes through zero, in the frequency range. In order to shift the resonance frequency in the 100-MHz-1-GHz frequency range, Permalloy thin films have been intensively investigated with respect to their low anisotropy [2]. For an optimal tuning of the frequency resonance, several solutions have been discussed in the literature to decrease the anisotropy field with respect to a significant increase of the permeability.…”

“…Co-Zr thin-film alloys have been widely studied for their soft magnetic properties [2]- [5]. axial anisotropy with an out-of-plane component prevents from reaching resonance frequency below 1 GHz [6].…”