During the preparation process of the glass-covered magnetic amorphous wires, axial, radial, and azimuthal internal stresses are induced, determining their magnetic properties. We have proposed a calculation method of the internal stresses induced during the solidification of the metal and during the cooling from the solidification temperature to room temperature due to the difference between the thermal expansion coefficients of metal and glass. For ${\mathrm{Fe}}_{77.5}$ ${\mathrm{Si}}_{7.5}$ ${\mathrm{B}}_{15}$ glass-covered amorphous wires we found internal stresses of about ${10}^9$ Pa. The values and distribution of these stresses depend on the radius of the metal and on the thickness of the glass cover. The stress distribution coupled with the specific high positive magnetostriction leads to an easy axes distribution associated with a magnetic domain structure consisting of a cylindrical inner core with axial magnetization and a cylindrical outer shell with radial magnetization. The inner core leads to the appearance of a large Barkhausen jump at low axial fields. We have calculated the ratio ${\mathit{M}}_{\mathit{r}}$/${\mathit{M}}_{\mathit{s}}$ (the reduced remanence) as being of about 0.75–0.80. Magnetic measurements performed on samples prepared by us confirm the existence of the large Barkhausen jump but with a reduced remanence of about 0.95 that suggests the existence of a supplementary axial tensile stress. The dependence of the reduced remanence on external tensile stresses for wires covered by glass and after the glass removal confirms the existence of the supplementary stress whose value was estimated as being of the order of ${10}^8$ Pa.

The magnetic characteristics of FINEMET type glass-coated nanowires and submicron wires are investigated by taking into account the structural evolution induced by specific annealing all the way from a fully amorphous state to a nanocrystalline structure. The differences between the magnetic properties of these ultrathin wires and those of the thicker glass-coated microwires and “conventional” wires with similar structures have been emphasized and explained phenomenologically. The domain wall propagation in these novel nanowires and submicron wires, featuring a combination between an amorphous and a crystalline structure, has also been studied, given the recent interest in the preparation and investigation of new materials suitable for the development of domain wall logic applications.

We investigate the evolution of the magneto-impedance (MI) response of ${\mathrm{Fe}}_{\mathrm{73.5}}{\mathrm{Cu}}_{\mathrm{1}}{\mathrm{Nb}}_{\mathrm{3}}{\mathrm{Si}}_{\mathrm{13.5}}{\mathrm{B}}_{\mathrm{9}}$ glass-covered wires with the annealing temperature, starting from the as-cast amorphous state up to 600 $°\mathrm{C}.$ As-cast FeCuNbSiB amorphous glass-covered wires display a MI ratio of about 1%, this value increasing with the annealing temperature to about 5% for 550 $°\mathrm{C}$ when the nanocrystalline phase appears. For wires which have had the glass removed, the MI ratio increases from 5% for the as-cast amorphous state up to 28% after the appearance of the nanocrystalline phase. The MI is larger than that found in CoFeSiB amorphous wires after glass removal. Annealing over 550 $°\mathrm{C}$ leads to a decrease of the MI ratio for both glass-covered samples and samples with the glass coating removed. The results demonstrate the role of soft magnetic properties on the sensitivity of the MI effect.

Results on the preparation and magnetic characterization of rapidly solidified amorphous glass-coated nanowires are reported. Rapidly solidified nanowires have been investigated by means of bulk and surface hysteresis loop measurements, scanning electron microscopy, and ferromagnetic resonance. Domain wall velocity has been measured to demonstrate the suitability of the new nanowires for spintronic applications. Changes in composition, in the thickness of the glass coating, and nanowire dimensions allow extensive tailoring of the domain wall mobility.