![]() ![]() High and positive magnetostriction coefficient values are observed in Fe-rich compositions (typically λ s ≈ 35–40 × 10 −6). The magnetostriction coefficient of as-prepared amorphous magnetic materials is determined mostly by chemical composition of the alloy 24. The magnetoelastic anisotropy, K me, is determined by the magnetostriction coefficient, λ s, and the internal stress, σ i, through the following expression 8, 14, 23: In spite of the absence of magnetocrystalline anisotropy the other sources of magnetic anisotropy, like magnetoelastic and shape anisotropies determine the magnetic properties of the glass-coated microwires with amorphous structure. The Taylor Ulitovsky technique involves simultaneous rapid solidification of the metallic nucleus with diameters 0.5–90 μm surrounding by the glass coating with thickness 0.5–20 μm 12, 22. The thinnest amorphous magnetic wires can be prepared by the Taylor Ulitovsky method described elsewhere 8, 12, 21. For these reason, low dimensional and cost effective soft magnets are especially demanded for a number of emerging applications 8, 17, 18, 19, 20. Use of low dimensional soft magnets allows reduction of magnetic devices. ![]() Furthermore, rapid quenching from the melt preparation technique is quite fast and inexpensive 3, 4, 5.Īmong other aspects significant for technological applications of soft magnets are the dimensionality, the cost efficiency and the tuneability of magnetic properties. Accordingly, excellent magnetic softness can be achieved in as-prepared samples without need of thermal treatments and post-processing. However, magnetic softness of amorphous magnetic materials is originated by the liquid-like structure characterized by the absence of crystalline structure and hence defects typical for crystals 14, 15, 16. Accordingly, optimization of magnetic softness of crystalline magnetic materials involves durable and costly annealing 12, 14. Indeed, defects of the crystalline structure such as grain boundaries, texture, dislocation density, etc., notably alter the magnetic softness of crystalline materials. However, amorphous wires prepared using melt quenching provide a number of great advantages, such as excellent magnetic softness combined with better mechanical properties 13, 14. To a great extend these properties are related to cylindrical geometry and therefore can be observed in either amorphous or crystalline wires with rather different dimensions 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12. These properties of magnetic wires are essentially relevant for emerging industries, i.e., magnetic sensors, electrical engineering, medicine, informatics, magnetic recording, electronic surveillance among others. Magnetic nano-micro wires can present fast domain wall (DW) propagation observed in diverse families of magnetic wires 1, 2, 3, 4, as well as extremely excellent magnetic softness and giant magnetoimpedance (GMI) effect observed mostly in amorphous and nanocrystalline magnetic microwires 5, 6, 7, 8. Consequently, stress annealing enabled us to design the magnetic anisotropy distribution beneficial for optimization of either GMI effect or DW dynamics. Observed decreasing of the half-width of the EMF peak in stress-annealed microwires can be associated to the decreasing of the characteristic DW width. We assumed that the outer domain shell with transverse magnetic anisotropy associated to stress-annealing induced transverse magnetic anisotropy affects the travelling DW in a similar way as application of transversal bias magnetic field allowing enhancement the DW velocity. An improvement of the circumferential permeability in the nearly surface area of metallic nucleus is evidenced from observed magnetic softening and remarkable GMI effect rising. Beneficial effect of stress-annealing on GMI effect and DW dynamics is associated with the induced transverse magnetic anisotropy. We observed a remarkable improvement of domain wall (DW) mobility, DW velocity, giant magnetoimpedance (GMI) effect and magnetic softening at appropriate stress-annealing conditions. ![]()
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