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Comprehensive Summary: Compounds with magnetic bistability is highly attractive for the construction of switches, thermal sensors, information‐storage media and memory devices. Herein, we report a crystalline fullerene radical anion salt [Na(THF)5]C60 (1), obtained by the reduction of C60 with Na in solution, which exhibits magnetic bistability accompanied with one magnetostructural transition, giving low temperature (LT), high temperature (HT) phases and a metastable phase. Fullerene radical anions (C60•‐) in the structure were found arranged into a three‐dimensional close‐packed honeycomb subnetwork with hollow channels occupied by complex cations [Na(THF)5]+ as spacers. The magnetic bistability is attributed to structural transitions as the LT−IT phase transition was associated with the orientational disorder of fullerene anions and the distortion of the complex cations [Na(THF)5]+ in the 3D packing of fullerene anions. [ABSTRACT FROM AUTHOR]

The title radical R⋅, synthesized by reduction of the corresponding cation R+, is thermally stable up to ~380 K in the crystalline state under anaerobic conditions. With SQUID magnetometry, single‐crystal and powder XRD, solid‐state EPR and TG‐DSC, reversible spin‐Peierls transition between diamagnetic and paramagnetic states featuring ~10 K hysteretic loop is observed for R⋅ in the temperature range ~310–325 K; ΔH=~2.03 kJ mol−1 and ΔS=~6.23 J mol−1 K−1. The transition is accompanied by mechanical movement of the crystals, i. e. by thermosalient behavior. The low‐temperature diamagnetic P‐1 polymorph of R⋅ consists of R⋅2 π‐dimers arranged in (...R⋅2...)n π‐stacks; whereas the high‐temperature paramagnetic P21/c polymorph, of uniform (...R⋅...)n π‐stacks. With the XRD geometries, CASSCF and broken‐symmetry DFT jointly suggest strong antiferromagnetic (AF) interactions within R⋅2 and weak between R⋅2 for the (...R⋅2...)n stacks; and moderate AF interactions between R⋅ for the (...R⋅...)n stacks. The fully hydrocarbon archetype of R⋅ does not reveal the aforementioned properties. Thus, the fluorinated 1,3,2‐benzodithiazolyls pave a new pathway in the design and synthesis of metal‐less magnetically‐bistable materials. [ABSTRACT FROM AUTHOR]

The advantageous applications of magnetic bistable microwires have emerged during long-lasting research. They have a wide range of applications in the scientific sphere or technical practice. They can be used for various applications, including magnetic memories, biomedicine, and sensors. This manuscript is focused on the last-mentioned application of microwires—sensors—discussing various digital signal processing techniques used in practical applications. Thanks to the highly sensitive properties of microwires and their two stable states of magnetization, it is possible to perform precise measurements with less demanding digital processing. The manuscript presents four practical signal-processing methods of microwire response using three different experiments. These experiments are focused on detecting the signal in a simple environment without an external magnetic background, measuring with the external background of a ferromagnetic core, and measuring in harsh conditions with a strong magnetic background. The experiments aim to propose the best method under various conditions, emphasizing the quality and signal processing speed of the microwire signal. [ABSTRACT FROM AUTHOR]

There is an immense research interest in molecular hybrid materials posing novel magnetic properties for usage in spintronic devices and quantum technological applications. Although grafting magnetic molecules onto carbon nanotubes (CNTs) is nontrivial, there is a need to explore their single molecule magnetic (SMM) properties post-grafting to a greater degree. Here, we report a one-step chemical approach for lanthanide-EDTA (Ln = GdIII, 1; TbIII, 2 and DyIII, 3) chelate synthesis and their effective grafting onto MWCNT surfaces with high magnetic bistability retention. The magnetic anisotropy of an Ln-CNT hybrid molecular system by replacing the central ions in the hybrid complex was studied and it was found that system 1 exhibited a magnetization reversal from positive to negative values at 70 K with quasi-anti-ferromagnetic ordering, 2 showed diamagnetism to quasi-ferromagnetism and 3 displayed anti-ferromagnetic ordering as the temperature was lowered at an applied field of 200 Oe. A further analysis of magnetization (M) vs. field (H) revealed 1 displaying superparamagnetic behavior, and 2 and 3 displaying smooth hysteresis loops with zero-field slow magnetic relaxation. The present work highlights the importance of the selection of lanthanide ions in designing SMM-CNT hybrid molecular systems with multi-functionalities for building spin valves, molecular transistors, switches, etc. [ABSTRACT FROM AUTHOR]

The advantageous applications of magnetic bistable microwires have emerged during long-lasting research. They have a wide range of applications in the scientific sphere or technical practice. They can be used for various applications, including magnetic memories, biomedicine, and sensors. This manuscript is focused on the last-mentioned application of microwires—sensors—discussing various digital signal processing techniques used in practical applications. Thanks to the highly sensitive properties of microwires and their two stable states of magnetization, it is possible to perform precise measurements with less demanding digital processing. The manuscript presents four practical signal-processing methods of microwire response using three different experiments. These experiments are focused on detecting the signal in a simple environment without an external magnetic background, measuring with the external background of a ferromagnetic core, and measuring in harsh conditions with a strong magnetic background. The experiments aim to propose the best method under various conditions, emphasizing the quality and signal processing speed of the microwire signal.

Molecular toolkit is a crucial part of futuristic spintronics and quantum information technologies. Magnetic bistability is the basis for such applications, which can be achieved by spin crossover (SCO) systems and single molecular magnets (SMMs). The SCO phenomenon relies on cooperativity, while the latter defies it. For the first time, a recent report by Galán-Mascarós and coworkers outlined the occurrence of memory effect in a trinuclear iron spin crossover system through its incorporation in a solid-state diamagnetic matrix or as a dilute solution. The fact that this molecule can show a memory effect on dilution, almost at a molecular level, opens up new possibilities for SCO systems doubling up as single-molecule magnets at elevated temperatures in the foreseeable future. Memory effect in a trinuclear iron spin crossover system by incorporating it in a solid-state diamagnetic matrix or as a dilute solution opens up new vistas in molecular magnetism is detailed in this article. [ABSTRACT FROM AUTHOR]

Amorphous microwires have attracted substantial attention in the past decade because of their useful technological applications. Their bistable magnetic response is determined by positive or negative magnetostriction, respectively. First-order reversal curves (FORC) are a powerful tool for analyzing the magnetization reversal processes of many-body ferromagnetic systems that are essential for a deeper understanding of those applications. After theoretical considerations about magnetostatic interactions among microwires, this work introduces a systematic experimental study and analysis of the FORC diagrams for magnetostrictive microwires exhibiting an individually bistable hysteresis loop, from a single microwire to sets of an increasing number of coupled microwires, the latter considered as an intermediate case to the standard many-body problem. We performed the study for sets of quasi-identical and different hysteretic microwires where we obtained the coercivity H c and interaction H u fields. In the cases with relevant magnetostatic interactions, FORC analysis supplies deeper information than standard hysteresis loops since the intrinsic fluctuations of the switching field generate a complex response. For sets of microwires with very different coercivity, the coercivity distributions of the individual microwires characterize the FORC diagram. [ABSTRACT FROM AUTHOR]

Polymetallic complexes with covalently bridged metal centers that interact magnetically are important in the molecular magnetism field, with binuclear compounds receiving special attention because they represent the simplest type of multinuclear species with covalently bridged metal centers. Herein, we report the synthesis and properties of two new binuclear FeII complexes, namely, {[Fe(abpt-TPE)(NCS)2]2(bpym)}·2MeOH·2MeCN (1) and {[Fe(abpt-TPE)(NCS)2]2(bpym)}·2CH2Cl2 (2) (bpym = 2,2′-bipyrimidine). The crystal structure is analyzed at different temperatures, and its properties are analyzed by variable-temperature magnetic susceptibility and variable-temperature fluorescence emission spectroscopy tests. Variable-temperature magnetic susceptibility measurements of two binuclear compounds show different types of magnetic behavior. Complex 1 exhibits two-step spin transition behavior with an intermediate state near 150 K (Tc1 = 191 K, Tc2 = 111 K); 1 undergoes an [LS–LS] ↔ [LS–HS] ↔ [HS–HS] spin transition during thermal induction. On the other hand, complex 2 exhibits intramolecular antiferromagnetic coupling, with J = −0.47 cm−1. The analysis of correlations between the structural characteristics and different types of magnetic behaviors for two binuclear complexes, revealed that the different magnetic behaviors shown by the two complexes are attributable to different degrees of [FeN6] octahedral distortion caused by different lattice solvents, ligand strain and crystal stacking. [ABSTRACT FROM AUTHOR]

There is an immense research interest in molecular hybrid materials posing novel magnetic properties for usage in spintronic devices and quantum technological applications. Although grafting magnetic molecules onto carbon nanotubes (CNTs) is nontrivial, there is a need to explore their single molecule magnetic (SMM) properties post-grafting to a greater degree. Here, we report a one-step chemical approach for lanthanide-EDTA (Ln = GdIII, 1; TbIII, 2 and DyIII, 3) chelate synthesis and their effective grafting onto MWCNT surfaces with high magnetic bistability retention. The magnetic anisotropy of an Ln-CNT hybrid molecular system by replacing the central ions in the hybrid complex was studied and it was found that system 1 exhibited a magnetization reversal from positive to negative values at 70 K with quasi-anti-ferromagnetic ordering, 2 showed diamagnetism to quasi-ferromagnetism and 3 displayed anti-ferromagnetic ordering as the temperature was lowered at an applied field of 200 Oe. A further analysis of magnetization (M) vs. field (H) revealed 1 displaying superparamagnetic behavior, and 2 and 3 displaying smooth hysteresis loops with zero-field slow magnetic relaxation. The present work highlights the importance of the selection of lanthanide ions in designing SMM-CNT hybrid molecular systems with multi-functionalities for building spin valves, molecular transistors, switches, etc.

Amorphous microwires have attracted substantial attention in the past decade because of their useful technological applications. Their bistable magnetic response is determined by positive or negative magnetostriction, respectively. First-order reversal curves (FORC) are a powerful tool for analyzing the magnetization reversal processes of many-body ferromagnetic systems that are essential for a deeper understanding of those applications. After theoretical considerations about magnetostatic interactions among microwires, this work introduces a systematic experimental study and analysis of the FORC diagrams for magnetostrictive microwires exhibiting an individually bistable hysteresis loop, from a single microwire to sets of an increasing number of coupled microwires, the latter considered as an intermediate case to the standard many-body problem. We performed the study for sets of quasi-identical and different hysteretic microwires where we obtained the coercivity Hc and interaction Hu fields. In the cases with relevant magnetostatic interactions, FORC analysis supplies deeper information than standard hysteresis loops since the intrinsic fluctuations of the switching field generate a complex response. For sets of microwires with very different coercivity, the coercivity distributions of the individual microwires characterize the FORC diagram.

Polymetallic complexes with covalently bridged metal centers that interact magnetically are important in the molecular magnetism field, with binuclear compounds receiving special attention because they represent the simplest type of multinuclear species with covalently bridged metal centers. Herein, we report the synthesis and properties of two new binuclear FeII complexes, namely, {[Fe(abpt-TPE)(NCS)2]2(bpym)}·2MeOH·2MeCN (1) and {[Fe(abpt-TPE)(NCS)2]2(bpym)}·2CH2Cl2 (2) (bpym = 2,2′-bipyrimidine). The crystal structure is analyzed at different temperatures, and its properties are analyzed by variable-temperature magnetic susceptibility and variable-temperature fluorescence emission spectroscopy tests. Variable-temperature magnetic susceptibility measurements of two binuclear compounds show different types of magnetic behavior. Complex 1 exhibits two-step spin transition behavior with an intermediate state near 150 K (Tc1 = 191 K, Tc2 = 111 K); 1 undergoes an [LS–LS] ↔ [LS–HS] ↔ [HS–HS] spin transition during thermal induction. On the other hand, complex 2 exhibits intramolecular antiferromagnetic coupling, with J = −0.47 cm−1. The analysis of correlations between the structural characteristics and different types of magnetic behaviors for two binuclear complexes, revealed that the different magnetic behaviors shown by the two complexes are attributable to different degrees of [FeN6] octahedral distortion caused by different lattice solvents, ligand strain and crystal stacking.

Friction plays a pivotal role in the sliding-mode triboelectric energy harvester (TEH), which not only enables the charge transfer between two dielectrics, but also influences the energy harvesting performance by affecting the dynamic response of the TEH. How to evaluate the effects of the friction on TEHs is important for optimizing TEHs in engineering practices. In order to analyze the effects of the friction on the dynamic response and evaluate the energy harvesting performance of TEHs, the paper models the friction of a devised non-linear TEH based on the Coulomb friction model and the Macro-slip friction theory. The TEH equips a pair of magnets, rendering a switching between the bistability and the monostability by tuning the distance between two magnets. The dynamic model of the non-linear TEH is established by the extended Hamilton principle. The effects of friction in sliding-mode TEH are dissected in detail. The influences of parameters on both the mechanical and electrical responses are also systemically studied to explore an optimal energy harvesting performance in the low-frequency range. This work provides a guideline for designing and accurately analyzing a sliding-mode TEH. [ABSTRACT FROM AUTHOR]

Systematic experimental results on the Matteucci effect in torsioned magnetostrictive FeSiB microwire are introduced, observed during the propagation of a single domain wall (DW) under the action of axial driving magnetic field, Hdr. These data are discussed, reviewing current bibliography models and proposing new perspectives. The unidirectional DW velocity is quantified by voltage induced in tiny pickup coils along the microwire. The Matteucci electromotive force (emf) induced between the microwire's ends is associated with depinning and annihilation of the DW, introducing a new method to measure DW velocity. The emf amplitude is proportional to the DW velocity and the time derivative of the azimuthal magnetization, tailored by applied torsion. The data confirm the existence of net values of azimuthal magnetization and spontaneous torsion induced during fabrication. The clockwise/counterclockwise applied torsion dependence of Matteucci emf and DW velocity are experimentally determined for parallel and antiparallel Hdr. Asymmetric behaviors are observed for both, the sense of applied torsion and the direction of Hdr. The experimental data are discussed in terms of the magnetoelastic anisotropy introduced by torsion. Through analysis of the DW dynamics, such asymmetric behaviors are interpreted as a magnetochiral effect derived from the change of chirality of the propagating wall. [ABSTRACT FROM AUTHOR]

Applications in security and electronic surveillance require a combination of excellent magnetic softness with good mechanical and anticorrosive properties and low dimensionality. We overviewed the feasibility of using glass-coated microwires for electronic article surveillance and security applications, as well as different routes of tuning the magnetic properties of individual microwires or microwire arrays, making them quite attractive for electronic article surveillance and security applications. We provide the routes for tuning the hysteresis loops’ nonlinearity by the magnetostatic interaction between the microwires in the arrays of different types of amorphous microwires. The presence of neighboring microwire (either Fe- or Co-based) significantly affects the hysteresis loop of the whole microwires array. In a microwires array containing magnetically bistable microwires, we observed splitting of the initially rectangular hysteresis loop with a number of Barkhausen jumps correlated with the number of magnetically bistable microwires. Essentially, nonlinear and irregular hysteresis loops have been observed in mixed arrays containing Fe- and Co-rich microwires. The obtained nonlinearity in hysteresis loops allowed to increase the harmonics and tune their magnetic field dependencies. On the other hand, several routes allowing to tune the switching field by either postprocessing or modifying the magnetoelastic anisotropy have been reviewed. Nonlinear hysteresis loops have been also observed upon devitrification of amorphous microwires. Semihard magnetic microwires have been obtained by annealing of Fe–Pt–Si microwires. The observed unique combination of magnetic properties together with thin dimensions and excellent mechanical and anticorrosive properties provide excellent perspectives for the use of glass-coated microwires for security and electronic surveillance applications.

We studied the effect of applied tensile stresses on magnetic properties of Fe- and Co-rich amorphous glass-coated microwires. Rising of magnetic anisotropy field upon tensile stress in Co-rich glass-coated microwires is described by a linear dependence. Furthermore, decrease of magnetic susceptibility upon tensile stress is observed in Co-rich microwires. A monotonous increase in the coercivity and the switching field upon tensile applied stress is observed for as-prepared Fe-rich microwire. Stress induced magnetic bistability consisting of transformation of hysteresis and onset of rectangular hysteresis loop upon tensile stress, σ , of about 22.5 MPa is observed in stress-annealed Fe-rich microwires. Such stress-induced magnetic bistability results in considerable growing of coercivity and remanent magnetization in stress-annealed Fe-rich microwires. The rising in the coercivity and the switching field upon applied tensile stresses in stress-annealed Fe-rich microwires with stress induced magnetic bistability (at σ > 22.5 MPa) is roughly described by the σ ½ dependence, as previously reported for the wires with spontaneous magnetic bistability. Consequently, stress-annealing of Fe-rich microwire allows beneficial enhancement of the stress dependence of coercivity. Observed dependencies are discussed considering stress dependence of the magnetostriction coefficient in Co-rich glass-coated microwires, internal stresses redistribution and domain structure rearrangement in stress-annealed Fe-rich microwires upon applied tensile stresses. Image 1 • Linear increase in the magnetic anisotropy field upon stress in Co-rich microwires. • Decrease in the magnetic susceptibility upon applied stress in Co-rich microwires. • Observation of stress induced magnetic bistability in stress-annealed Fe-rich microwires. • Enhanced stress dependence of coercivity in stress-annealed Fe-rich microwires. • Observation of σ ½ dependence of switching field in stress-annealed Fe-rich microwires. [ABSTRACT FROM AUTHOR]

We present our experimental results on optimization of the magnetic softness in Fe-rich magnetic microwires by stress annealing. It is found that the magnetic softness and magnetoimpedance effect of the Fe-rich microwires can be considerably improved by annealing. The hysteretic properties and magnetoimpedance are considerably affected by the tensile stress applied during the annealing. Experimental dependencies are attributed to changes in magnetic domain structure of magnetic wires in particular decrease of the inner axially magnetized core volume in expense of increase of the outer domain shell with transverse magnetization orientation. Observed stress-induced anisotropy and related changes of magnetic properties are discussed considering internal stresses relaxation and “back-stresses.” [ABSTRACT FROM AUTHOR]

A remarkable improvement of magnetic softness and giant magnetoimpedance (GMI) effect of Co-rich glass-coated microwire is observed at appropriate Joule-heating regimes. Under optimal Joule-heating conditions, we observed GMI ratio up to 650% and coercivity of about 3 A/m. Observed experimental dependencies are discussed considering induced magnetic anisotropy, internal stresses relaxation, and radial distribution of the magnetic anisotropy. [ABSTRACT FROM AUTHOR]

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.

Amorphous ferromagnetic materials in the form of microwires are of interest for the development of various sensors. This paper analyzes and argues for the use of microwires of two basic compositions of Co71Fe5B11Si10Cr3 and Fe3.9(4.9)Co64.82B10.2Si12Cr9(8)Mo0.08 as stress/strain and temperature sensors, respectively. The following properties make them suitable for innovative applications: miniature dimensions, small coercivity, low anisotropy and magnetostriction, tunable magnetic structure, magnetic anisotropy, and Curie temperature by annealing. For example, these sensors can be used for testing the internal stress/strain condition of polymer composite materials and controlling the temperature of hypothermia treatments. The sensing operation is based on the two fundamental effects: the generation of higher frequency harmonics of the voltage pulse induced during remagnetization in wires demonstrating magnetic bistability, and magnetoimpedance.

• The new opportunity of glass-coated microwires for bio- application is presented. • The application for pressure measuring inside a human cranium is confirmed. • FeSiBP glass-coated microwire as a contactless sensor of the intracranial pressure. • The high theoretical sensibility about 0.3 Pa can be achieved. The given paper presents one new opportunity of glass-coated microwires for biomedical applications, especially the possibility of pressure measuring inside a human cranium. The application allows noninvasive and contactless sensing of the intracranial pressure (ICP) using FeSiBP glass-coated microwire for a sensor in a model of skull. First, the measurement of the mechanical dependence of the switching time dt on the microwire shows almost linear progression. In this case the middle tensile sensibility S T (slope value) of microwire is 1.84 μs/MPa. The studied microwire, implanted in the skull as a sensor, could measure intracranial parameters simultaneously at any time, only by attaching the probe from the outside of the head. The experimental measurements have been carried out on the skull model with the water balloon, which has similar properties and Young's modulus of cerebral membrane - dura. The measurements, in the range of values corresponding to normal intracranial pressure show, that the switching time dt monotonously increases with increasing hydrostatic pressure in the water balloon, where the average tensile sensibility S T is about 38 ns/Pa. The high theoretical sensibility about 0.3 Pa can be achieved. This approach makes this technology very interesting for the practical application. [ABSTRACT FROM AUTHOR]

• Rapidly solidified amorphous submicronic wires exhibit fast moving domain walls. • Controlled nucleation generates domain walls moving towards each other. • The interaction of such moving domain walls is accurately controllable. • The results are important for sensing and magnetic logic applications. Rapidly solidified submicronic amorphous glass-coated wires are unique materials due to their specific combination of reduced diameters, large sample length, and bistable magnetic behavior, of interest for sensing and magnetic logic applications due to their fast-moving magnetic domain walls. Here we report on the interaction of such domain walls moving within amorphous (Co 0.94 Fe 0.06) 72.5 Si 12.5 B 15 glass-coated submicronic wires with nearly zero magnetostriction. The main part of the complex experimental set-up includes multiple pick-up coils evenly distributed along a sample and two nucleation coils placed at its ends. If there is no signal in the nucleation coils, the magnetization switches starting from one end to the other, with a single moving domain wall being sequentially detected by the pick-up coils. Magnetization reversal can be initiated at both wire ends by means of nucleation fields generated using the corresponding nucleation coils. By adjusting the amplitudes of these fields, one can guide the two associated domain walls to move towards each other and to interact in any desired place along the submicronic amorphous sample. Hence, it is possible to control with accuracy the precise individual domain walls that interact on the wire axis, and with a certain precision, the location in which the two domain walls would interact. The collision of the domain walls gives rise to a double amplitude peak in the pick-up coil that detects it. The results show that the interaction of domain walls in amorphous submicronic wires is completely controllable, which is significant for their future applications. [ABSTRACT FROM AUTHOR]

We developed technological procedures for preparation of filiform nanostructures (FNSs) on the basis of stretching microwires with magnetic material cores. It is shown that disruptions of the microwire core occur for these materials during technological process of stretching due to relatively high melting temperature of magnetic alloys. As a result, FNSs with elongated magnetic inclusions are produced. An installation for the production of FNSs as well as an experimental complex for measuring magnetic properties of the produced magnetic FNSs is described in this paper. The morphology of the produced FNSs from microwires with magnetic bistability is investigated by means of scanning electron microscopy, while magnetic properties, such as magnetic response with remagnetizing pulses, hysteresis loop, and coercive force, are investigated on the developed experimental complex. The magnetic interaction during remagnetizing processes of several microwires with different coercive forces assembled in a bunch, as well as the reaction of a bunch assembled from a big number of bistable mirowires of two types with different coercive forces (soft magnetic and hard magnetic cores) upon increasing external magnetic field are also investigated. Some potential applications of the produced magnetic structures are suggested. [ABSTRACT FROM AUTHOR]

A linear position sensor based on the unique functionality of the magnetically bistable glass-coated microwire is presented. Despite the magnetic nature of the sensor, it is possible to separate the external magnetic field's contribution, thus providing independence from parasitic external magnetic fields. With the presented unique approach, it is possible to transfer the linear position of the piston into the switching time and obtain high sensitivity down to 1 µm. [Display omitted] • Linear position sensor with down to 1 µm sensitivity based on bistable magnetic microwire. • Linear position measuring is temperature and external magnetic field independent. • 0.19 % measurement error within the temperature range 15–50 °C. [ABSTRACT FROM AUTHOR]

Results on the roles played by the magnetoelastic and magnetostatic anisotropy terms in the magnetic behavior of glass-coated magnetostrictive amorphous nanowires prepared by means of rapid solidification are reported. Their contributions have been analyzed both experimentally, through hysteresis loop measurements, and theoretically, using micromagnetic simulations. All the investigated samples exhibit a magnetically bistable behavior, characterized by a single-step magnetization reversal when the applied field reaches a critical threshold value, called switching field. The combined interpretation of the experimental and theoretical data allows one to understand the effect of the magnetoelastic term on the value of the switching field, on one hand, and the effect of the magnetostatic term on the nucleation mechanism on the other, both with an essential impact on the characteristics of the nanowires’ magnetic bistability. The results are crucial for understanding the basic magnetic properties of these novel rapidly solidified ultrathin magnetic wires, as well as for tailoring their properties according to the specific requirements of various sensing applications. [ABSTRACT FROM AUTHOR]

The magnetic behavior of zero-magnetostrictive rapidly solidified amorphous nanowires has been investigated in order to understand their magnetic bistability. The study has been performed both experimentally – based on inductive hysteresis loop measurements – and theoretically, by means of micromagnetic simulations. Experimental hysteresis loops have shown that the amorphous nanowires display an axial magnetic bistability, characterized by a single-step magnetization reversal when the applied field reaches a critical value called switching field. The simulated loops allowed us to understand the effect of shape anisotropy on coercivity. The results are key for understanding and controlling the magnetization processes in these novel nanowires, with important application possibilities in new miniaturized sensing devices. [ABSTRACT FROM AUTHOR]

The temperature dependence of the magnetic behaviour of Fe-based glass-coated amorphous microwires with positive magnetostriction has been studied in the temperature range from 5 to 300 K. For long enough microwires, hysteresis loops are squared shaped in the whole temperature range denoting the existence of a large domain with axial easy axis. For short microwires, magnetic bistability is partially lost near room temperature but may be recovered at low temperature. This is interpreted considering the influence of the shape anisotropy: in short wires the demagnetizing field may become large enough to destroy the single domain structure. The influence of coating is also considered by studying microwires with different coating thickness. Transverse magnetoelastic anisotropy up to around 400 MPa can be induced at low temperature as a consequence of the difference in thermal expansion coefficients between metallic nucleus and insulating coat. Additional changes in the low-temperature loops have been identified to be a consequence of the way how the microwires are fixed to the sample´s holder. Under particular circumstances transverse anisotropy induced at low temperature may destroy the bistable behavior.En este trabajo se resumen los más recientes resultados alcanzados relativos al comportamiento magnético de microhilos amorfos ricos en Fe cubiertos de capa aislante en función de la temperatura de medida (en el rango de 5 a 300 K). Estos microhilos, debido a su elevada magnetostricción, presentan comportamiento magnético biestable cuando su longitud supera un valor crítico determinado por la intensidad de la anisotropía magnética axial. Esta anisotropía depende en particular del espesor de la cubierta protectora de Pyrex, de modo que al reducir la temperatura se inducen fuertes tensiones mecánicas (hasta 400 MPa) como consecuencia de la diferencia de valor del coeficiente de expansión térmica con el núcleo metálico. Se comprueba asímismo que el modo de sujección del microhilo al portamuestras puede generar fuertes tensiones de compresión y dar lugar a la desaparición de comportamiento biestable.

• A vibro-impact grating-structured triboelectric energy harvester is developed. • The bistable mechanism via pairs of magnets broadens frequency bandwidth. • Increasing grating segment number of films improves harvesting efficiency. • Vibration amplitude affects enhancement effect of segment number on power yield. Currently, in the field of triboelectric energy harvesting, there have been extensive studies of material science and manufacturing aspects, but much less on structural vibration aspect, especially for grating-structured triboelectric energy harvesters. This paper presents an in-depth theoretical and experimental investigation on both the structural and electrical dynamics of a novel triboelectric energy harvester, which contains grating-patterned films and a magnetic bistable mechanism for dual enhancement of power yield. It operates in the in-plane sliding mode. Friction is heavily involved during the oscillation of the slider of the harvester, and vibro-impact is likely to occur. A mechanical model of the harvester is established, which covers friction, magnetic force and impact. Based on the film geometry, an electrical model is built accordingly. Numerical simulations are carried out to investigate the effects of the potential wells created by the magnets, acceleration amplitude of excitation, segment number of the grating-patterned films, from the perspectives of both structural and electrical dynamics. The bistable mechanism is proved to shift the frequency band of the harvester to lower frequency values, which is nearly twice as wide as that of the same harvester without this mechanism. When the vibration amplitude of the oscillator is smaller than the width of the grating units on the films, increasing the segment number can dramatically enhance the output voltage. Once the vibration amplitude exceeds the width of the units, the output voltage rises slowly with the increase of the segment number. Harvesters having three types of films with different segment numbers (0, 1 and 2) are made and tested. The root-mean-square output voltage is found to increase from 0.82 V to 3.88 V at 5 Hz when the segment number increases from 0 to 2. Over 40 light-emitting diodes can be lit by the harvester with a rectifying circuit. This work affords an opportunity for designing more efficient triboelectric energy harvesters with a broad bandwidth. [ABSTRACT FROM AUTHOR]

Abstract: The domain wall (DW) propagation in magnetically bistable Fe74Si11B13C2 amorphous microwires with metallic nucleus diameters of 12–16μm has been investigated in order to explain high DW velocities observed in Sixtus–Tonks like experiments. In micrometric wires, the boundary between two head-to-head domains is very elongated. The DW mobility normal to the wall surface is reduced by the domain aspect ratio and is in the range of a few m/s/Oe in the linear regime. The experimental results in the viscous regime could be quantitatively explained in terms of the domain length and normal mobility limited by the eddy currents and spin relaxation losses. [Copyright &y& Elsevier]

Abstract: A heteroleptic nickel-bis-1,2-dithiolene ion–pair complex, [BzQl][Ni(dmit)(mnt)] (where BzQl+ =1-(benzyl)quinolinium; dmit2− =2-thioxo-1,3-dithiole-4,5-dithiolate, mnt2− =maleonitriledithiolate), was synthesized and characterized structurally, which exhibited novel magnetic bistability. The compound crystallized in triclinic system with space group P-1. The anions and cations form alternating layered alignments, and the anionic layer is built by the irregularly heteroleptic [Ni(dmit)(mnt)]− chains, where the neighboring anions are connected via lateral-to-lateral S…S contacts of dmit2− ligands. The temperature dependences of magnetic susceptibility follow the S=½ Heisenberg alternating linear-chain model in high-temperature phase and Curie–Weiss law in low-temperature phase. [Copyright &y& Elsevier]

Amorphous glass-coated microwires exhibit excellent magnetic properties that make them very suitable to be employed as sensing elements in devices for technological applications. In the present work, we review a few examples. Some applications are based on the magnetostrictive character of Fe based wires that show also bistable magnetic behaviour. It includes magnetic labels or magnetoelastic pens for security applications. In the case of non-magnetostrictive wires, and based on the giant magnetoimpedance effect, they can be employed as tips in spin polarized magnetometry or as stress sensors. Most recently, a new family of microwires has been introduced, multilayered microwires, which offer quite interesting properties and can be employed as sensing elements in multifunctional sensor devices. [ABSTRACT FROM AUTHOR]

The temperature dependence of the magnetic behaviour of Fe-based glass-coated amorphous microwires with positive and large magnetostriction constant (around 30 ppm at room temperature) has been studied in the temperature range from 2 to 390 K. For long enough microwires (about 10 mm), hysteresis loops are squared shaped denoting the existence of a single domain structure and the magnetization reversal by a single Barkhausen jump. In the case of short microwires (around 2 mm) drastic changes are observed at low temperature where such magnetic bistability is lost. This is interpreted considering the influence of shape anisotropy: for short wires the demagnetizing field becomes large enough to destroy the single domain structure. On the other hand, the changing magnetoelastic anisotropy induced by coating when reducing measuring temperature is also considered.Particular emphasis is additionally done to study the dependence of the switching field for magnetization reversal and that of its fluctuations on temperature and frequency of exciting field. [Copyright &y& Elsevier]

The effect of thermal treatments such as conventional furnace annealing (CA) and annealing under tensile stress (SA) on the hysteretic magnetic properties of Fe74B13Si11C2 glass-coated microwires has been studied. CA treatment does not change the character of the hysteresis loop but coercivity, Hc, slightly decreases due to the internal stress relaxation. Under certain SA conditions (annealing temperature, Tann>300 °C, applied stress, σ>700 MPa) the hysteresis loop becomes inclined with transverse anisotropy field about 1500 A/m. This modification of the hysteresis loop has been interpreted in terms of the change of the easy magnetization direction from axial to a transverse direction.On the other hand, samples subjected to stress annealing show noticeable (12%) magneto-impedance effect in spite of their large magnetostriction. Finally, application of tensile stresses to the stress-annealed sample results in the recovering of the rectangular hysteresis loop typical for the as-prepared state. This processing allows the tailoring of magnetic anisotropy in these microwires which is of interest for technological purposes. [Copyright &y& Elsevier]