The influence of magnetic anisotropy, post-processing conditions, and defects on the domain wall (DW) dynamics of amorphous and nanocrystalline Fe-, Ni-, and Co-rich microwires with spontaneous and annealing-induced magnetic bistability has been thoroughly analyzed, with an emphasis placed on the influence of magnetoelastic, induced and magnetocrystalline anisotropies. Minimizing magnetoelastic anisotropy, either by the selection of a chemical composition with a low magnetostriction coefficient or by heat treatment, is an appropriate route for DW dynamics optimization in magnetic microwires. Stress-annealing allows further improvement of DW velocity and hence is a promising method for optimization of DW dynamics in magnetic microwires. The origin of current-driven DW propagation in annealing-induced magnetic bistability is attributed to magnetostatic interaction of outer domain shell with transverse magnetization orientation and inner axially magnetized core. The beneficial influence of the stress-annealing on DW dynamics has been explained considering that it allows increasing of the volume of outer domain shell with transverse magnetization orientation at the expense of decreasing the radius of inner axially magnetized core. Such transverse magnetic anisotropy can similarly affect the DW dynamics as the applied transverse magnetic field and hence is beneficial for DW dynamics optimization. Stress-annealing allows designing the magnetic anisotropy distribution more favorable for the DW dynamics improvement. Results on DW dynamics in various families of nanocrystalline microwires are provided. The role of saturation magnetization on DW mobility improvement is discussed. The DW shape, its correlation with the magnetic anisotropy constant and the microwire diameter, as well as manipulation of the DW shape by induced magnetic anisotropy are discussed. The engineering of DW propagation through local stress-annealing and DW collision is demonstrated.

A new smart concrete aggregate design as a candidate for applications in structural health monitoring (SHM) of critical elements in civil infrastructure is proposed. The cement-based stress/strain sensor was developed by utilizing the stress/strain sensing properties of a magnetic microwire embedded in cement-based composite (MMCC). This is a contact-less type sensor that measures variations of magnetic properties resulting from stress variations. Sensors made of these materials can be designed to satisfy the specific demand for an economic way to monitor concrete infrastructure health. For this purpose, we embedded a thin magnetic microwire in the core of a cement-based cylinder, which was inserted into the concrete specimen under study as an extra aggregate. The experimental results show that the embedded MMCC sensor is capable of measuring internal compressive stress around the range of 1–30 MPa. Two stress sensing properties of the embedded sensor under uniaxial compression were studied: the peak amplitude and peak position of magnetic switching field. The sensitivity values for the amplitude and position within the measured range were 5 mV/MPa and 2.5 µs/MPa, respectively.

We have studied the evolution of domain wall dynamics during the devitrification of amorphous and nanocrystalline ${\text{Fe}}_{73.5}{\text{Cu}}_1{\text{Nb}}_3{\text{Si}}_{11.5}{\text{B}}_{11}$ microwires. Depending on the annealing temperature range, three different regimes in the domain wall dynamics can be considered for these materials. Annealing below the Curie temperature, $T_{\text{c}}$, of the alloy leads to the stabilization of the domain structure and a strong temperature dependence of the domain wall dynamic parameters. However, annealing above $T_{\text{c}}$ leads to a destabilization of domain patterns and a decrease in the domain wall damping in one order of magnitude. Finally, annealing above the crystallization temperature, $T_{\text{x}}$, leads to the appearance of the nanocrystalline state that is structurally very stable. In this case, the domain wall velocity is very fast due to the lack of magnetic anisotropy and extremely stable with the temperature.

The influence of post-processing conditions on the magnetic properties of amorphous and nanocrystalline microwires has been thoroughly analyzed, paying attention to the influence of magnetoelastic, induced and magnetocrystalline anisotropies on the hysteresis loops of Fe-, Ni-, and Co-rich microwires. We showed that magnetic properties of glass-coated microwires can be tuned by the selection of appropriate chemical composition and geometry in as-prepared state or further considerably modified by appropriate post-processing, which consists of either annealing or glass-coated removal. Furthermore, stress-annealing or Joule heating can further effectively modify the magnetic properties of amorphous magnetic microwires owing to induced magnetic anisotropy. Devitrification of microwires can be useful for either magnetic softening or magnetic hardening of the microwires. Depending on the chemical composition of the metallic nucleus and on structural features (grain size, precipitating phases), nanocrystalline microwires can exhibit either soft magnetic properties or semi-hard magnetic properties. We demonstrated that the microwires with coercivities from 1 A/m to 40 kA/m can be prepared.

The evolution of the magnetic domain structure with the applied torsion has been studied by means of the Bitter technique on high magnetostrictive Fe73.5Si13.5B9Nb3Cu1 amorphous wires. A drastic change in domain patterns is observed by applying a very low torsional strain value as small as 2.4 (2πrad∕m) in the wire. The domain structure on the wire surface changes from a maze configuration, with zigzag walls, to a helical one. When the magnitude of the applied torsion is increased, both in clockwise or counterclockwise senses, a change in the values for the domain width as well as the wall angle tilting with respect to the wire axis are clearly observed, showing a saturation value of 45° for an applied torsional strain equal or higher than 10 (2πrad∕m). Also, the coercive field variation with the applied torsion shows a minimum value of 26Am−1 just for a torsional strain of 2.4 (2πrad∕m), suggesting that the internal and the applied helical anisotropies are then balanced, at least partially, resulting in the softest magnetic state for the amorphous wire with respect to the coercive field of 40Am−1 for the untwisted wire.