Mechanical stress offers a powerful way of controlling magnetic domain structures and domain wall dynamics in amorphous microwires. In this work, we investigate and compare the effects of reversible and irreversible stress application using two complementary approaches: mechanical bending and non-magnetic copper coating. Irreversible stress introduced by copper deposition generates a permanent redistribution of internal stresses transmitted through the glass coating into the metallic core. This modifies the magnetoelastic anisotropy and stabilizes specific domain wall configurations, enabling field driven transformations between energetically close helical and elliptical domain wall states and providing a mechanism for tuning domain wall mobility and pinning.Reversible stress is realized through controlled bending of the microwire, producing a well-defined spatial distribution of mechanical stress across the cross-section, with compressive stress localized at the inner surface. Under these conditions, helical surface magnetic structures are stabilized but fully disappear upon removal of the deformation, allowing direct separation of reversible magnetoelastic effects from permanent structural changes.The irreversible stress engineering and reversible mechanical modulation produce a wide range of magnetic responses, spanning static stabilization of domain configurations and dynamic stress assisted transitions during magnetization reversal. This dual approach provides new opportunities for precise control of magnetic anisotropy, domain wall dynamics, and bistability, and is highly relevant for the development of stress sensitive magnetic sensors and adaptive microwire based devices.

The effect of non-magnetic tungsten coatings on the magnetic behavior of glass-coated Co-based amorphous microwires is investigated. Tungsten layers with thicknesses ranging from 300 to 1000 nm were deposited onto the glass sheath, and their influence on magnetization reversal, magnetic bistability, and domain wall dynamics was examined. Hysteresis measurements reveal a clear distinction between coated and uncoated regions: uncoated segments exhibit smooth, non-bistable magnetization reversal, whereas tungsten-coated regions show pronounced magnetic bistability. The observed bistability originates from mechanical stresses generated in the tungsten film and transferred through the glass coating to the metallic core, thereby modifying the magnetoelastic anisotropy. Spatially resolved measurements reveal a gradual reduction of the magnetization jump near the coating edges, indicating the formation of inclined or partial (helical) bistable states due to stress relaxation. Tungsten thickness is identified as a key control parameter, with thicker coatings producing stronger and more uniform stress fields that stabilize axial bistability, while thinner coatings favor partial bistability and enhanced transverse susceptibility. Sixtus-Tonks measurements further confirm thickness-dependent variations in domain wall pinning and coercivity. These results demonstrate that non-magnetic tungsten coatings provide an effective stress-mediated approach for tailoring magnetic states in amorphous microwires for bistable and giant magnetoimpedance-based sensing applications.

We evaluated how annealing affects the magnetic properties and Giant Magnetoimpedance (GMI) response of Co68.7Fe4Si11B13Ni1Mo2.3 glass-coated microwires with nearly zero magnetostriction. We used microwires with fixed dimensions and annealed them at 350 degrees C for 30, 45, 60, and 90 min. X-ray diffraction confirmed that the amorphous structure was maintained after the annealing. Annealing brought substantial changes in the hysteresis loops. At first, the loops were almost linear and unhysteretic and, hence, showed low remanence, Mr, about 0.045. After annealing, they acquired rectangular shapes with Mr approximate to 0.95, making the microwires magnetically bistable. The GMI response improved the most. As-prepared microwires started with the GMI ratio, Delta Z/Z, about 370%. After annealing for 30 min, the GMI ratio increased to about 500% -a huge 31% boost at practical frequencies (100-150 MHz). But, if we pushed annealing to 90 min, performance actually dropped to about 400%. Accordingly, with careful control of annealing conditions we can obtain microwires with unique combination of magnetic properties, i.e. showing both magnetic bistability and outstanding GMI sensitivity. This kind of performance makes these microwires especially promising for cutting-edge magnetic sensing and biomagnetic detection technologies.

Fe-3 wt.% Si (Fe-3Si) gas atomised powder is used to fabricate laser-directed energy deposition (laser-DED) test specimens. The magnetic and mechanical properties of the as-built and three post-processed samples, including annealing and hot isostatic pressing (HIP), are evaluated in terms of the microstructure. The diffusion of silicon and the formation of Si-rich zones are observed when the material is annealed at 700 degrees C for 5 h, resulting in a dramatic reduction of the mechanical properties due to the formation of brittle precipitates. The best static soft magnetic properties combined with good mechanical properties are obtained by annealing at 1150 degrees C for 2 h, resulting in high magnetic saturation (2.02 T), low coercive field (89 A/m), high elongation (similar to 30 %) and high tensile strength (similar to 480 MPa). Additionally, the core loss of the as-built sample and the sample annealed at 1150 degrees C for 2 h is dissected and compared with that of the flat-rolled Fe-Si material. The as-built conditions provide better performance under low frequency AC conditions due to lower skin effect, giving a core loss of W15/50 = 28.5 W/kg, while maintaining good mechanical and magnetic properties. This work shows that further research into the additive manufacturing of low-frequency machines is needed to make this technology an effective option for the production of the future next-generation engines.

We systematically studied the influence of annealing on the magnetic properties and Giant Magnetoimpedance (GMI) effect of Co-Fe-Si-B-Ni-Mo glass-coated microwires. Upon thermal treatment, a remarkable transformation in the hysteresis loop shape from inclined to almost perfectly rectangular is observed. Simultaneously, a significant enhancement in the GMI ratio, $\Delta \mathbf{Z} / \mathbf{Z}$, is achieved, increasing from an initial $\Delta \mathrm{Z} / \mathrm{Z} \sim 370 {\%}$ up to 470% accompanied by a significant modification in the magnetic field dependence of the GMI ratio $(\Delta \mathrm{Z} / \mathrm{Z})$, characterized by a shift of the GMI peaks to much lower magnetic fields. Observed hysteresis loop change is associated to a change in the magnetization reversal mechanism from magnetization rotation towards single DW propagation in the inner axially magnetized single domain. Direct measurements confirm this, revealing fast and uniform DW propagation with velocities up to $850 \mathrm{m} / \mathrm{s}$ in samples annealed at 350 °C. The observed changes in magnetic properties are interpreted considering the internal stress relaxation which promotes a substantial change in the domain structure of studied microwire.

In this paper, the impact of annealing at different temperatures (973 K, 1073 K, and 1123 K for 1 h) on the magnetic and microstructural properties of MnFePSi-based glass-coated microwires is studied. Annealing significantly influences the magnetic and microstructural properties of Mn–Fe–P–Si glass-coated microwires. XRD analysis reveals that increasing the annealing temperature leads to a notable increase in the Fe2P phase content, reaching a maximum at 1123 K, while simultaneously reducing the presence of secondary phases observed in the as-prepared sample. The reduction in secondary phases in Mn–Fe–P–Si-based microwires, grain size, and internal stress relaxation have a profound impact on their magnetic behavior. High coercivity values are observed in both the as-prepared and annealed samples. However, annealing at higher temperatures (1073 K and 1123 K) results in a significant reduction in coercivity, decreasing from 1200 Oe for the sample annealed at 973 K to 300 Oe and 150 Oe, respectively. In addition, the sample annealed at 1123 K for 1 h shows a notable paramagnetic behavior for loops measured from 200 K to 300 K. Meanwhile, the other samples show ferromagnetic behavior for all measured temperatures from 5 to 300 K. This study highlights the significant potential for tailoring and modifying various magnetic properties of Mn–Fe–P–Si glass-coated microwires, including metamagnetic phase transitions, magnetic behavior, and the control of magnetic response (hardness/softness). Such tailored properties make Mn–Fe–P–Si glass-coated microwires promising candidates for a wide range of applications.

In this article we present our experimental results on the effect of high temperature annealing on magnetic and structure performance of NiMnGa-based glass coated microwires. The samples were annealed at 1173 K and 1273 K for 1h. The as-prepared sample exhibits weak ferromagnetic behaviour with magnetic remanence near to zero and average coercivity about 6 Oe. Annealing of NiMnGa microwires leads to increase in coercivity up to 230 Oe for the sample annealed at 1273 K. Additionally, high-temperature annealing induces martensitic transformation (MT). Annealing significantly influences the Curie temperature (Tc) of the samples, bringing it closer to room temperature, thereby making them more suitable for magnetic solid-state refrigeration applications. The observed changes can be attributed to several factors, such as internal stress relaxation, nanocrystalline structure, recrystallization processes, and variations in the magnetic ordering of phases present in the as-prepared and annealed states. While the insulating and flexible glass coating enhances the mechanical properties of the microwires, it is important to acknowledge that it can also significantly affects their magnetic properties. The current results confirm the stability of ferromagnetic and martensitic transformation of nanocrystalline NiMnGa-based glass-coated wires after heat treatment up to 1273 K.

The accelerating global demand for sustainable and efficient energy storage has driven substantial interest in supercapacitor technology due to its superior power density, fast charge–discharge capability, and long cycle life. However, the low energy density of supercapacitors remains a key bottleneck, limiting their broader application. This review provides a comprehensive and focused overview of the latest breakthroughs in supercapacitor research, emphasizing strategies to overcome this limitation through advanced material engineering and device design. We explore cutting-edge developments in electrode materials, including carbon-based nanostructures, metal oxides, redox-active polymers, and emerging frameworks such as metal–organic frameworks (MOFs) and covalent organic frameworks (COFs). These materials offer high surface area, tunable porosity, and enhanced conductivity, which collectively improve the electrochemical performance. Additionally, recent advances in electrolyte systems—ranging from aqueous to ionic liquids and organic electrolytes—are critically assessed for their role in expanding the operating voltage window and enhancing device stability. The review also highlights innovations in device architectures, such as hybrid, asymmetric, and flexible supercapacitor configurations, that contribute to the simultaneous improvement of energy and power densities. We identify persistent challenges in scaling up nanomaterial synthesis, maintaining long-term operational stability, and integrating materials into practical energy systems. By synthesizing these state-of-the-art advancements, this review outlines a roadmap for next-generation supercapacitors and presents novel perspectives on the synergistic integration of materials, electrolytes, and device engineering. These insights aim to guide future research toward realizing high-energy, high-efficiency, and scalable supercapacitor systems suitable for applications in electric vehicles, renewable energy storage, and next-generation portable electronics.

Glass-covered microwires were studied after spiral annealing. Before annealing, the sample was laid out in the form of a geometric spiral with a given curvature. After annealing, the sample was straightened and analyzed. Using a magneto-optical technique, both new surface magnetic structures induced by spiral stress annealing and magnetization reversal processes were studied. Spiral stress annealing causes the formation of an internal stress gradient from tension to compression across the sample. This stress gradient smoothly changes along the length of the microwire. A gradual change in the anisotropy field with the length of the sample was observed on the surface of the microwire.We highlight two main results depending on the longitudinal location of the observation: the effect of the transverse stress gradient on the motion of domain walls and the effect of the transverse stress gradient on the process of magnetic domain nucleation.

This review article provides an in-depth analysis of recent advancements in the fabrication, structural characterization, and magnetic properties of Heusler alloy glass-coated microwires, focusing on Co2FeSi alloys. These microwires exhibit unique thermal stability, high Curie temperatures, and tunable magnetic properties, making them suitable for a wide range of applications in spintronics, magnetic sensing, and biomedical engineering. The review emphasizes the influence of geometric parameters, annealing conditions, and compositional variations on the microstructure and magnetic behavior of these materials. Detailed discussions on the Taylor–Ulitovsky fabrication technique, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM) provide insights into the structural properties of the microwires. The magnetic properties, including room-temperature behavior, temperature dependence, and the effects of annealing, are thoroughly examined. The potential applications of these microwires in advanced spintronic devices, magnetic sensors, and biomedical technologies are explored. The review concludes with future research directions, highlighting the potential for further advancements in the field of Heusler alloy microwires.

We studied the influence of annealing on the magnetic properties and microstructure of ultrathin (metallic nucleus diameter ≈ 5 μm, total diameter ≈ 19 μm) Heusler-type NiMnGa glass-coated microwires prepared using the Taylor–Ulitovsky method. The as-prepared NiMnGa microwires exhibit unexpectedly strong magnetic anisotropy, characterized by a coercivity exceeding 3 kOe at room temperature. Furthermore, their Curie temperature (Tc) lies above room temperature. Additionally, a spontaneous exchange bias of approximately 120 Oe is observed in the as-prepared sample at 100 K. Annealing the microwires leads to a decrease in coercivity, spontaneous exchange bias, and Tc values. Notably, the annealing process shifts the Tc of the samples closer to room temperature, making them more suitable for magnetic solid-state refrigeration applications. Moreover, the hysteresis observed in the temperature dependence of magnetization for the samples annealed for 1 h and 2 h, along with the magnetic softening observed at around 260 K, is attributed to a first-order phase transformation. The observed changes are discussed in the context of internal stress relaxation after annealing, the nanocrystalline structure of both the as-prepared and annealed samples, the recrystallization process, and the magnetic ordering of phases identified in the as-prepared sample and those appearing during recrystallization. The glass coating on microwires offers benefits like better flexibility and resistance to damage and corrosion. However, it is important to recognize that this coating can substantially alter the microwires’ magnetic characteristics. Consequently, precise control over the annealing process is vital to obtain the specific martensitic transformation needed.

Amorphous soft magnetic composites (SMCs) are characterised by low-volume fraction of magnetic material and therefore, poor magnetic permeability and saturation magnetisation. In this work, amorphous powder (Fe0.425 Co0.30 Si0.125 B0.15)96.5Nb3Cu0.5) is coated with 10 and 15 vol.% of resin and consolidated at high pressures (up to 2 GPa). Maximisation of particles packaging is obtained by mixing fractions of 0-10 µm and 20-45 µm in a volume ratio of 27:73 vol.%, respectively. Magnetic properties and power losses of SMCs made from 0-10 µm fraction and from the mixed fractions are compared. SMCs made from mixed fractions result in higher permeability but increased power losses. Low power losses (Pcv = 5850 mW/cm3 at f = 1 MHz, B = 50 mT), highest permeability (µ’ = 43.4) and highest saturation magnetisation (Ms = 0.82 T) are obtained with the SMC made from the mixed fractions after annealing and subsequent resin infiltration.

This work presents an innovative approach to obtain anisotropic Nd-Fe-B powder from isotropic gas atomized powder. The new process was developed using a ternary Nd-Fe-B alloy, without the requirement for additional heavy rare earth or other critical raw materials. It comprises the following steps: (a) gas atomization to produce a polycrystalline isotropic powder; (b) annealing at high temperature to induce grain growth; (c) hydrogen decrepitation to obtain a monocrystalline powder; and (d) hydrogenation-disproportionation-desorption-recombination to obtain the final ultrafine anisotropic particles. The final particle shape is polygonal, which should improve the injection molding characteristics of current powder. The final powder exhibits both high remanence (0.97 T) and coercivity (1354 kA/m) for laboratory batch sizes, which is a result of its anisotropic ultrafine microstructure. Thus, gas atomization is considered a feasible alternative to casting methods as a first step to produce powders for anisotropic bonded magnet.

Fe-3Si gas atomised powder is coated with iron phosphate, epoxy resin and a hybrid of the two coatings to produce soft magnetic composites (SMCs). Consolidation of iron phosphate powders is performed by uniaxial compaction and field assisted sintering technology (FAST), whereas resin and hybrid coating are compaction by uniaxial compaction followed by curing. This study shows that the optimisation of the physical and magnetic properties of FAST-consolidated iron phosphate SMCs strongly depends on the coating thickness and the FAST cycle performed. Compact density, electrical resistivity, magnetic properties and power losses are discussed in terms of the type of coating and consolidation method. Overall, FAST consolidation results in lower coercivity and higher densification than cold pressing, producing higher saturation magnetisation and permeability. However, lower power losses (P) are obtained with the cold-pressed SMCs (P = 9040 mW/cm(3) at f = 1 MHz and B = 50 mT). In addition, the high ductility of the resin coating leads to a very thin layer between the Fe-3Si particles, thus maximising the permeability (mu' = 65). By contrast, the highest electrical resistivity (similar to 10(7) mu Omega cm) is obtained with the hybrid SMC due to the good coupling between the two coatings.

A preprocessing technique named “spiral annealing” was applied for the first time to magnetic microwires. In this process, the sample was arranged in a flat spiral shape during annealing, and subsequent measurements were conducted on the unbent sample with the induced stress distribution along and transverse to the sample. The research utilized both magnetic and magneto-optical methods. The anisotropy field magnitude in both the volume and surface of the microwire was measured, and for the first time, a direct correlation between the anisotropy field and the curvature of a spirally annealed microwire was established. Additionally, a connection between the type of surface domain structure and the degree of spiral curvature was identified. The preservation of the distribution of spiral annealing-induced magnetic properties both along and across the microwire is a key effect influencing the technological application of the microwire. The range of induced curvature within which a specific helical magnetic structure can exist was also determined. This insight links the conditions of spiral annealing to the selection of microwires as active elements in magnetic sensors.

We studied the MnFePSi glass-coated microwires (GCMWS) prepared by using Taylor-Ulitovsky technique at low magnetic fields and low temperatures. While regular ferromagnetic behavior has been observed at room temperature, anomalous magnetic behavior is observed for the glass-coated microwires samples. Notable metamagnetic phase transition is observed for bulk alloy sample from the magnetic hysteresis loops measured at 5 K. Meanwhile, extraordinary metamagnetic phase transition is seen at hysteresis loops measured at temperature below 100 K. In addition, M-H loops show harder magnetic properties compared to the bulk sample, where the coercivity, Hc, of glass-coated microwire is about 64 times higher than the one reported in bulk alloy. Additionally, the hysteresis loops of glass-coated microwires measured at temperature lower than 100 K show multistep magnetic behaviour. Zero Field Cooling (ZFC), Field Cooling (FC) and Field Heating (FH) curves of bulk samples show totally different magnetic behaviour compared to the microwire sample measured at the same conditions due to the different microstructure phases for the bulk and microwires samples. The present findings demonstrate the significant impact of drawing, quenching and stresses induced by glass-coating on the microstructure and magnetic characteristics of MnFePSi-metallic alloys as compared to their bulk form. Furthermore, we confirmed that, in contrast to the bulk form constraint, the Taylor-Ulitovsky process for metallic glass-coating microwires may alter the physical characteristics and extend the applications of MnFePSi alloys.

A novel Co-base soft magnetic powder with ultra-low coercivity was produced by inert gas atomisation. The as-atomised powder is fully amorphous owing to its high glass forming ability and the proper selection of atomisation conditions; it exhibits a very low coercivity (0.130Oe) mainly due to the low magnetostriction coefficient of Co-based alloys. After production, the powder was annealed at different temperatures between 300 and 600 ºC for 30minutes. Crystallisation started at around 575 ºC, which is the temperature of the first exothermic peak detected by differential scanning calorimetry. Annealing the powder at temperatures below 550 ºC develops only structural relaxation of the amorphous structure. The smallest coercivity (0.056Oe) was found in the sample annealed at 400 ºC. On the other hand, an increment of the coercivity of four orders of magnitude occurred after full crystallisation at 600 ºC (394.320Oe). From the analysis of the curves of anisotropy field distribution, it can be concluded that this Co-base alloy shows lower average anisotropy field, a more gaussian shape and a wider distribution than Fe-base alloys. This is explained by a lower magnetoelastic anisotropy and a more homogeneous distribution of the magnetic anisotropy. The powder exhibits a spherical shape that makes it very suitable as ferromagnetic phase to manufacture powder cores with extremely low hysteresis loss for medium-high frequency applications.

Ultrafast magnetization switching through the single domain wall (DW) propagation has been reported in amorphous micrometric and submicrometric wires. However the performance of prospective devices utilizing DW propagation is determined by the degree to which DW propagation can be controlled. In this article, we propose a novel method for effectively controlling the single DW propagation in a specially designed array consisting of two magnetic microwires by the stray field from magnetically softer microwires. We have experimentally demonstrated that the DW velocity of magnetically harder Fe-rich microwire in such a linear array is affected by the stray field of magnetically softer Co-rich microwire. Additionally, the domain wall can be trapped in the Fe-rich microwire by the stray field produced by the Co-rich microwire in such a linear array. The observed effect of magnetostatic interaction depends on the position of the Co-rich microwire in such a linear array. Controllable domain wall propagation observed in such a linear array can be a useful tool for simple and more flexible ways of controllable trapping and braking of single DWs in Fe-rich microwires showing spontaneous magnetic bistability.

Most studies on soft magnetic composites (SMC) have focused on traditional compaction. However, this consolidation method leads to low densities and therefore, poor magnetic properties. For this reason, this work focuses on the study of an iron phosphate (Fe 3 (PO 4 ) 2 ) coating to develop SMCs consolidated through a novel field-assisted sintering technology (FAST) and compares it with traditional compaction. A direct relationship is demonstrated between the thickness of the coating obtained and the amount of reagent added to the synthesis as well as the inverse relationship between the thickness of the coating and the powder/acetone ratio. By contrast, thermal analysis shows that the desired phase Fe 3 (PO 4 ) 2 is stable up to 900 degrees C. Between 900 and 960 degrees C, iron phosphate decomposes into Fe-P and SiO 2 . At higher temperatures, the decomposition process is completed, and the Fe-P phase reacts with Fe-3Si particles, resulting in an FeSiP matrix with a non-continuous layer of surrounding SiO 2 . The highest compact density and static magnetic properties are obtained for the SMC prepared with 2 wt% H 3 PO 4 and a powder/acetone ratio of 2.5 g/mL consolidated by FAST, providing a density of 6.59 g/ cm 3 , a magnetic saturation of 1.752 T and a coercivity of 313.4 A/m. In addition, this SMC results in the highest permeability in the entire audio-frequency range (40 up to 100 kHz) as well as high electrical resistivity (3.18 & sdot; 10 5 mu Omega cm) and the lowest power losses up to 10-20 kHz (31.7 mW/cm 3 at B = 50 mT and f = 10 kHz). However, cold-press consolidation leads to higher operating frequencies, reaching a permeability of 24 up to 1 MHz, and the lowest power losses for frequencies greater than 10-20 kHz (414 mW/cm 3 at 100 kHz and B = 50 mT) due to the reduction of eddy currents obtained by the higher electrical resistivity and lower number of coating defects.

For Fe-rich glass-coated microwires to be a competitive option for magnetic technologies, the enhancing and tuning of their properties is necessary, and therefore, a better understanding of these processes is also needed. In this work, two Fe microwires with different geometries are subjected to both conventional and current annealings to study their effects. Results show a general enhancement of magnetic softness and domain wall dynamics after both treatments, also suggesting an earlier onset of crystallization in thin samples.