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The power spectra of the Barkhausen noise of Ni1-xMnx was studied to determine the effects of the degree of disorder and of the temperature on domain wall dynamics. The results showed that increased manganese concentration altered the magnetic order from a classical ferromagnetism to a probable mixed state characterized by longitudinal ferromagnetic ordering and spin glass-like transverse frezing.

The field-dependent transverse permeability characterization of amorphous thin films with nominal composition [Fe.sub.73.5][Cu.sub.1][Nb.sub.3][Si.sub.13.5][B.sub.9] is performed for a wide range of frequencies. The dynamic and static magnetic properties of these films are investigated and the obtained results are discussed in terms of the stress contribution to the magnetic anisotropy of the samples.

Magnetoimpedance-based ferromagnetic resonance (FMR) studies of annealed Co68.15Fe4.35Si12.5B15 glass-covered amorphous microwires under stress are reported. Results concluded that a longitudinal anisotropy dominates the microwire behavior under zero stress.

Magnetoimpedence and magnetization measurements are performed in Joule-heated glass-covered amorphous microwires, and impedance spectra are measured at different magnetic fields. The outer shell domains evolve from a circumferential, to a helical structure in the case of the annealed samples, and the inner core evolves from a domain structure typical of a radial anisotropy to a longitudinal one, when the inner core and the outer shell domain structure are observed.

The giant magnetoimpedance of glass-covered amorphous microwires with nominal composition Co70.4Fe4.6Si15B10 is investigated. It is found that the annealing by Joule heating produced a fast crystallization of the sample, decreasing the magnetoimpedance ratio and rounding the peaks observed in Z versus H curves.

Observes magneto-impedance effects in amorphous Fe[sub 73.5]Cu[sub 1]Nb[sub 3]Si[sub 13.5]B[sub 9] thin films. Achievement of large magneto-impedance values in field-annealed samples; Observation of transverse magneto-impedance effects with magnitudes comparable to longitudinal case; Elaboration of the results in terms of appropriate magnetic permeability.

Examines the role of magnetic anisotropy in the magnetoimpedance effect in amorphous ferromagnets. Presence of transverse magnetic anisotropy in the field-annealed samples; Effect of transverse annealing on magnetoimpedance spectra; Saturation of magnetoimpedance and magnetization of the sample.

Abstract: The amorphous alloy Fe90Zr7B3 containing alpha-iron nanocrystallites (known commercially as NANOPERM®) is produced in ribbons by melt spinning and presents magnetic properties that allow its wide applicability in magnetic shielding, low loss RF transformers, choke coils, magnetic sensors and flux-gate magnetometers. In this work, we present a study of the effect of the annealing process realized at different temperatures on the magnetic properties of this material. Comparisons of experimental results of ferromagnetic resonance (FMR) and magnetization measurements show that the precipitation of alpha-iron phase causes the reduction of the coercive field and the in-plane magnetic anisotropy by about 70% in ribbons annealed for 1h at temperatures between 250 and 350°C. [Copyright &y& Elsevier]

Abstract: We study the magnetic properties at high frequency of new structures of the tri-layer samples. The magnetoimpedance effect was analyzed in FM/i/Cu/i/FM sandwiched layers, where the ferromagnetic layer (FM) is, in fact, a multilayered film [F (10nm)+Cu (1nm)]×50 and F is the amorphous ferromagnetic alloy Fe73.5Cu1Nb3Si13.5B9 and i is an isolating layer produced by magnetron sputtering. The effect of, both, the probe current frequency (in the range 10MHz–1.8GHz) and the dimensions of the magnetic and non-magnetic layers of the MI response were investigated. A comparison between samples with and without the isolating layer is discussed. MI ratios of 220% were obtained for samples at 180MHz with a ferromagnetic and Cu width layers of 2 and 1mm, respectively. [Copyright &y& Elsevier]