Development of magnetic microwires for magnetic sensor applications

Thin magnetic wires can present excellent soft magnetic properties (with coercivities up to 4 A/m), Giant Magneto-impedance effect, GMI, or rectangular hysteresis loops combined with quite fast domain wall, DW, propagation. In this paper we overview the magnetic properties of thin magnetic wires and post-processing allowing optimization of their magnetic properties for magnetic sensor applications. We concluded that the GMI effect, magnetic softness or DW dynamics of microwires can be tailored by controlling the magnetoelastic anisotropy of as-prepared microwires or controlling their internal stresses and domain structure by appropriate thermal treatment.This work was funded by Spanish MCIU under PGC2018-099530-B-C31 (MCIU/AEI/FEDER, UE) by the Government of the Basque Country under PIBA 2018-44 projectand by the University of Basque Country under the scheme of “Ayuda a Grupos Consolidados” (Ref.: GIU18/192)

The Comparison of Direct and Indirect Methods for Determining the Magnetocaloric Parameters in the Heusler Alloy Ni50Mn34.8In14.2B

The magnetocaloric properties of the Ni50Mn34.8In14.2B Heusler alloy have been studied by direct measurements of the adiabatic temperature change (ΔTAD(T,H)) and indirectly by magnetization (M(T,H)), differential scanning calorimetry, and specific heat (C(T,H)) measurements. The presence of a first-order ferromagnetic-paramagnetic transition has been detected for Ni50Mn34.8In14.2B at 320 K. The magnetocaloric parameters, i.e., the magnetic entropy change (ΔSM = (2.9-3.2) J/kgK) and the adiabatic temperature change (ΔTAD = (1.3-1.52) K), have been evaluated for ΔH = 1.8 T from CP(T,H) and M(T,H) data and from direct ΔTAD(T,H) measurements. The extracted magnetocaloric parameters are comparable to those of Gd

Martensitic transformation, magnetic and magnetocaloric properties of Ni–Mn–Fe–Sn Heusler ribbons

Melt-spun ribbons of nominal composition Ni50Mn36-xFexSn14 (x = 0, 2, and 3) were prepared by melt-spinning. The alloys undergo a martensitic transformation from L21 austenite to an orthorhombic 4O martensite on cooling, as determined by X-ray powder diffraction analysis. Replacement of Mn by Fe linearly reduces the characteristic temperatures of the martensitic transformation (the equilibrium temperature decreases from 328 to 285 K) and reduces the Curie temperature of the austenite phase (from 336 to 300 K), whereas the effect of the applied magnetic field on the martensite transition temperatures is negligible. Magnetic measurements (zero-field cooled, ZFC, and field cooled, FC, curves, AC susceptibility measurements) hint the coexistence of two different ferromagnetic martensitic magnetic phases. Moreover, the AC susceptibility measurements and the irreversibility of the ZFC and FC curves point towards the presence of antiferromagnetic and ferromagnetic interactions in the martensitic phase. All samples exhibit spontaneous exchange bias at 2 K, with double-shifted loops, whereas the evolution of the conventional exchange bias with the temperature agrees quite well with the behavior of ferromagnetic regions surrounded by spin-glass regions or with the coexistence of ferromagnetic–antiferromagnetic interactions. Ni50Mn36-xFexSn14 ribbons present a moderate inverse magnetocaloric effect (with a maximum of the magnetic entropy change of 5.7 Jkg−1K−1 for μ0H = 3 T for x = 3). It is worth to note that these materials feature a significant reservoir (up to 44 Jkg−1K−1 for x = 2) of magnetic entropy change, linked to the proximity of the austenitic ferromagnetic transition to the martensitic transformation.Se prepararon cintas hiladas por fusión de composición nominal Ni 50 Mn 36-x Fe x Sn 14 (x = 0, 2 y 3) mediante hilatura por fusión. Las aleaciones experimentan una transformación martensítica de austenita L2 1 a una martensita ortorrómbica 4O al enfriarse, según lo determinado por análisis de difracción de rayos X en polvo. La sustitución de Mn por Fe reduce linealmente las temperaturas características de la transformación martensítica (la temperatura de equilibrio desciende de 328 a 285 K) y reduce la temperatura de Curie de la fase austenita (de 336 a 300 K), mientras que el efecto del campo magnético aplicado sobre las temperaturas de transición martensítica es despreciable. Las mediciones magnéticas (campo cero enfriado, ZFC y campo enfriado, FC, curvas, medidas de susceptibilidad de CA) sugieren la coexistencia de dos fases magnéticas martensíticas ferromagnéticas diferentes. Además, las medidas de susceptibilidad AC y la irreversibilidad de las curvas ZFC y FC apuntan hacia la presencia de interacciones antiferromagnéticas y ferromagnéticas en la fase martensítica. Todas las muestras exhiben un sesgo de intercambio espontáneo a 2 K, con bucles de doble desplazamiento, mientras que la evolución del sesgo de intercambio convencional con la temperatura concuerda bastante bien con el comportamiento de regiones ferromagnéticas rodeadas por regiones spin-glass o con la coexistencia de interacciones ferromagnéticas-antiferromagnéticas. Ni50 Mn 36-x Fe x Sn 14 Las cintas presentan un efecto magnetocalórico inverso moderado (con un cambio de entropía magnética máximo de 5,7 Jkg −1 K −1 para μ 0 H = 3 T para x = 3). Vale la pena señalar que estos materiales presentan un reservorio significativo (hasta 44 Jkg −1 K −1 para x = 2) de cambio de entropía magnética, vinculado a la proximidad de la transición ferromagnética austenítica a la transformación martensítica

High performance soft magnetic materials

This book provides comprehensive coverage of the current state-of-the-art in soft magnetic materials and related applications, with particular focus on amorphous and nanocrystalline magnetic wires and ribbons and sensor applications. Expert chapters cover preparation, processing, tuning of magnetic properties, modeling, and applications. Cost-effective soft magnetic materials are required in a range of industrial sectors, such as magnetic sensors and actuators, microelectronics, cell phones, security, automobiles, medicine, health monitoring, aerospace, informatics, and electrical engineering. This book presents both fundamentals and applications to enable academic and industry researchers to pursue further developments of these key materials. This highly interdisciplinary volume represents essential reading for researchers in materials science, magnetism, electrodynamics, and modeling who are interested in working with soft magnets. Covers magnetic microwires, sensor applications, amorphous and nanocrystalline magnetic materials, and composite magnetic materials Discusses the fundamental physics and applications of the giant magnetoimpedance effect Presents tailoring of properties, characterization, and applications

GdFe-based nanostructured thin films with large perpendicular magnetic anisotropy for spintronic applications

In this study, we investigated the impact of geometric factors on the magnetic anisotropy of Gd-Fe alloy thin films deposited on nanoporous alumina membranes. By synthesizing Gd-Fe alloy nanostructure thin films with different hole diameters (ranging from 45 to 90 nm) and keeping the layer thickness and lattice parameters fixed at 45 nm and 105 nm, respectively, we observed a significant perpendicular magnetic anisotropy (PMA) in samples with hole diameter above 65 nm. The transition from in-plane to out-of-plane magnetization in Gd-Fe alloy nanostructure thin films occurred at a critical antidot hole diameter of 75 nm. The observed variations in coercivity and remanence with the nanohole diameter are attributed to substantial changes in the magnetization mechanisms induced by the nanoholes. This novel induction of PMA in Gd-Fe alloy nanostructure thin films through the manipulation of geometric parameters in the antidot arrays opens new possibilities for tailoring the magnetic behavior of ferromagnetic metals with pronounced PMA

Special Issue “Advances in Innovative Engineering Materials and Processes”

Successful progress in industrial development requires the use of cost-effective materials and advanced innovative materials with improved properties [...