A comprehensive analysis of magnetoimpedance (MI) phenomena in Fe-based nanocrystalline ribbons is presented in this paper. Giant MI responses have been observed in nanocrystalline samples annealed over the temperature range 490 and 600 • C. More than 400% increases of the MI ratio were obtained both in Fe 73.5 CuNb 3 Si 13.5 B 9 and in Fe 88 Zr 7 B 4 Cu ribbons. The sensitivity can reach a value larger than 60% Oe −1 in the field range 3-7.2 Oe at 800 kHz for Fe 73.5 CuNb 3 Si 13.5 B 9 ribbons. No MI effect was observed in an as-quenched amorphous Fe 88 Zr 7 B 4 Cu sample, because of its very low permeability. A mostly resistive feature was found in an as-quenched amorphous Fe 73.5 CuNb 3 Si 13.5 B 9 sample. The field dependences of the effective permeability show a typical transverse anisotropy property, and the development of the transverse anisotropy in naturally annealed Fe-based ribbons was analysed.

We report on the experimental investigation of nanosecond laser-induced Zn target damages versus the lens to sample distance (LTSD). The varieties of typical surface profiles associated with the evolutions of laser ignited plasma expansion were described in detail. According to the observed results, an established transient state of modified structure within an early phase of single-pulse laser ablation should play a critical role in the steps of final damage and plasma expanding. Due to the transient state, re-enhance absorption of laser energy will occur immediately in this case. On the other hand, it is deduced that the rise curves of transient absorption coefficient should obey an exponential growth, as the LTSD increasing from 103 mm to focal length ∼ 111 mm.

Magneto-impedance effects have been studied in amorphous and nanocrystalline ribbons. Large magneto-impedance responses have been obtained in nanocrystalline samples by applying a longitudinal DC field, but not in amorphous samples. It was found that the transverse field dependences of the resistance and the reactance of nanocrystalline samples show very broad peaks at relatively high fields (above 35 Oe), while the longitudinal magnetic responses show very sharp peaks at the field of 2 - 7 Oe, sharing some common features with those reported for Co-based amorphous wire and ribbon samples, and can be understood from the same mechanism. It was also found experimentally that the properties of the longitudinal and transverse field dependences of the effective permeability of nanocrystalline samples correlates with those of the impedance, showing a sharp decrease for the longitudinal applied field and a slow decrease for the transverse applied field at a corresponding field value and, the higher the effective permeability, the larger is the magneto-impedance effect at a fixed frequency. and a sensitivity of 20% at a low field (2 Oe) are obtained in this paper.

Abstrad Compositonally modulated FeSi/Si amorphous films with a fixed FeSi layer thickness and different Si layer thicknesses have been studied by -Fe conversion electron Masbauer spectroscopy at toom temperature. The results showed that, with decreasing Si layer thickness, the hyperfine fields of samples increased and the thickness of the interface dead layers arising from the atomic interdiffusion effect decreased. These are due to the couplingeffect between the magnetic layers. When the Si layers are thinner than 8.8 A, the direction of the magnetization is out of the film plane,