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A novel method has been used for accurately measuring low voltage signals (~[10.sup.-4] V) associated with inductance changes of bilayer thin-film sensors under bending stress. In this paper the architecture of the system is first presented, and then the design ideas and key technologies are followed. Initially, the frequency modulated signals were simulated with superimposed noise signals to test the demodulation performance of the written program. From the results, the expected output of the program was confirmed. Following this, the frequency modulation technique was used with actual sensor signals to measure the displacement of a bilayer thin film sensor. The results from the acquisition were compared with a previously developed amplitude modulation based setup, and it proved that the frequency modulation system provided a robust and accurate solution to evaluate magnetostrictive materials and their application in magnetic sensors. Index Terms--Amorphous magnetic films, frequency modulation, magnetic sensors, magnetostriction.

Amorphous magnetic glass-covered wires are of interest for basic research and potential applications. Their specific magnetic behavior originates in their very small diameters and in the high internal stresses induced during preparation. Removal of the glass cover leads to significant changes in their magnetic properties and behavior, thus improving their suitability for sensing applications. A thorough study of the changes produced by the glass removal implies the consideration of the changes produced in the internal stress distribution. We propose a method for the calculation of the residual internal stress distribution in wires obtained after the glass removal, based on the results of the magnetic measurements. The residual internal stress distribution allows us to explain the magnetic behavior of these wires. We also present the advantages of wires obtained after the glass removal from the practical point of view in comparison with those of conventional amorphous wires.

The changes in the magnetization mechanism with microwave dimensions in nearly zero magnetostrictive Co-based amorphous glass-coated microwaves are investigated. A reasonable estimation is obtained for the magnetostatic energy density in Co-based microwaves, which is based on hysteresis loop measurements with the applied tensile stress as a parameter.

The dependence of the inverse Wiedemann effect voltage on torsion applied along the Fe77.5Si7.5B15 glass covered amorphous wires before and after glass removal is investigated. Results show that both as-cast wires and wires annealed without torsion, increasing torsion value increases the induced voltage until it reaches a maximum. A good linearity of torsion response was also obtained for torsion annealed wires.

The sensitivity and magnitude of the giant magneto-impedance (GMI) effect in Fe(sub73.5)Cu(sub1)Nb(sub3)Si(sub13.5)B(sub9) nanocrystalline glass-covered wires and wires after glass removal, have been studied. Wires without glass exhibited a more sensitive GMI response, due to structural changes occurring during annealing. The obtained results illustrate the importance of good soft magnetic properties for a sensitive GMI response.

The anisotropy of Co(sub68.15)Fe(sub4.35)Si(sub12.5)B(sub15) wires was investigated using giant magnetoimpedance (GMI) and longitudinal magnetization curves, glass covered and after glass removal. The hysteresis and large Barkhausen jumps are in good agreement with that seen in the magnetization curves. The GMI response was calculated using deduced differential susceptibility from the model.

In this paper we report some results concerning the dependence of the pulsed voltage output on the exciting magnetic field and on the bias magnetic field applied at the exciting or receiving point, for [Fe.sub.77.5][Si.sub.7.5][B.sub.15] amorphous wires used as delay lines. The obtained results show a strong dependence of the pulsed voltage output on the values of the magnetic fields. Magnetic fields up to about 2000 A/m applied at the receiving point can be detected. Small magnetic fields applied at the exciting point can be detected using small values of the exciting magnetic field. Using this technique magnetic field sensors with high accuracy and sensitivity and absence of hysteresis can be realized. Such sensors can be formed in integrated arrays measuring the distribution of the magnetic field along the magnetostrictive delay line axis.

In this paper we report some results on the dependence of the pulsed voltage output on the applied torsion or tensile stress in [Fe.sub.77.5][Si.sub.77.5][B.sub.15] amorphous wires used as magnetostrictive delay lines. The obtained results show a not monotonic dependence of the response of the delay line on applied torsion. For applied tensile stress the response could be fitted by a linear curve for as-cast wires and by an exponential curve for annealed wires. The good ratio between minimum and maximum magnetostrictive delay line signals and the absence of hysteresis suggest the possibility to use this technique in load cells and torque sensors.

Various experimental studies are conducted to explain the magnetoresistance effect occurring in the Co-based amorphous glass-coated microwires with nearly zero magnetorestriction. The dimensions of the microwires are shown to be the main factor that determines the sharpness of the low peak magnetoresistance field.

The magnetic behavior of the glass-coated magnetic microwires, which are prepared from the [Fe.sub.87][Au.sub.2-x][Cu.sub.x][B.sub.11] alloy system, is described. The results have shown the effectiveness of composition control on the magnetic properties of Fe-(Au,Cu)-B microwires and have provided new opportunities for glass-coated microwires.

A new phenomenological model is described for the simulation of out-of-plane and in-plane hysteresis loops of magnetic/nonmagnetic multilayered nanowire arrays. This model has provided a convenient tool for studying the correlation between the hysteretic behavior and the geometry of nanowire arrays.