Magnetic Properties Of Materials Research Articles

3D imaging of magnetic domains in Nd2Fe14B using scanning hard X-ray nanotomography.

Nanoscale structural and electronic heterogeneities are prevalent in condensed matter physics. Investigating these heterogeneities in 3D has become an important task for understanding material properties. To provide a tool to unravel the connection between nanoscale heterogeneity and macroscopic emergent properties in magnetic materials, scanning transmission X-ray microscopy (STXM) is combined with X-ray magnetic circular dichroism. A vector tomography algorithm has been developed to reconstruct the full 3D magnetic vector field without any prior noise assumptions or knowledge about the sample. Two tomographic scans around the vertical axis are acquired on single-crystalline Nd2Fe14B pillars tilted at two different angles, with 2D STXM projections recorded using a focused 120 nm X-ray beam with left and right circular polarization. Image alignment and iterative registration have been implemented based on the 2D STXM projections for the two tilts. Dichroic projections obtained from difference images are used for the tomographic reconstruction to obtain the 3D magnetization distribution at the nanoscale.

A Calculation Method for Static Hysteresis Loop and its Applications

Background: Due to experimental equipment limitations, it is usually difficult to measure the quasi-static hysteresis loop at extremely low frequencies, which inevitably introduces errors in the static hysteresis model. Objective: This study aims to propose a method for calculating the static hysteresis loops of grainoriented silicon steel sheets so as to improve the accuracy of the static and dynamic hysteresis model. Methods: The parameters n0 and V0 in the magnetic field strength expression of the excess loss are determined by the measured losses within the range of 0-100Hz. Subsequently, the dynamic components in the quasi-static hysteresis loops are eliminated. Furthermore, a dynamic hysteresis model is established based on the loss and field separation theory, which incorporates the inverse Preisach model. Results: The dynamic hysteresis loops of the grain-oriented silicon steel sheets are measured in the range of 8-250Hz and compared with the results of both the improved model and the original model. Conclusion: Experimental results demonstrate the effectiveness and accuracy of the improved model. The proposed method for calculating static hysteresis loops has universal applicability and is meaningful for accurate simulation and prediction of magnetic properties in soft magnetic materials.

Gas-Induced Electrical and Magnetic Modulation of Two-Dimensional Conductive Metal-Organic Framework.

Controlled modulation of electronic and magnetic properties in stimuli-responsive materials provides valuable insights for the design of magnetoelectric or multiferroic devices. This paper demonstrates the modulation of electrical and magnetic properties of a semiconductive, paramagnetic metal-organic framework (MOF) Cu3(C6O6)2 with small gaseous molecules, NH3, H2S, and NO. This study merges chemiresistive and magnetic tests to reveal that the MOF undergoes simultaneous changes in electrical conductance and magnetization that are uniquely modulated by each gas. The features of response, including direction, magnitude, and kinetics, are modulated by the physicochemical properties of the gaseous molecules. This study advances the design of multifunctional materials capable of undergoing simultaneous changes in electrical and magnetic properties in response to chemical stimuli.

Comparison of a quasi Newton method using Broyden’s update formula and an adjoint method for determining local magnetic material properties of electrical steel sheets

Purpose Performing accurate numerical simulations of electrical drives, the precise knowledge of the local magnetic material properties is of utmost importance. Due to the various manufacturing steps, e.g. heat treatment or cutting techniques, the magnetic material properties can strongly vary locally, and the assumption of homogenized global material parameters is no longer feasible. This paper aims to present the general methodology and two different solution strategies for determining the local magnetic material properties using reference and simulation data. Design/methodology/approach The general methodology combines methods based on measurement, numerical simulation and solving an inverse problem. Therefore, a sensor-actuator system is used to characterize electrical steel sheets locally. Based on the measurement data and results from the finite element simulation, the inverse problem is solved with two different solution strategies. The first one is a quasi Newton method (QNM) using Broyden's update formula to approximate the Jacobian and the second is an adjoint method. For comparison of both methods regarding convergence and efficiency, an artificial example with a linear material model is considered. Findings The QNM and the adjoint method show similar convergence behavior for two different cutting-edge effects. Furthermore, considering a priori information improved the convergence rate. However, no impact on the stability and the remaining error is observed. Originality/value The presented methodology enables a fast and simple determination of the local magnetic material properties of electrical steel sheets without the need for a large number of samples or special preparation procedures.

Structural, Dielectric and Magnetic Properties of MFeNbO6 materials (M=Ti , Zr, Hf)

We study the structural, magnetic and electronic properties of MFeNbO6 materials (where A = Ti, Zr or Hf). TiFeNbO6 crystallises with the disordered rutile structure with the P42/mnm space group. Increasing the ionic radii of the M4+ cation going from Ti4+ (0.605 Å) to Zr4+ (0.72 Å) and Hf4+ (0.710 Å) results in a buckling of the octahedral chains with these materials crystallising with the disordered α-PbO2 structure (space group Pbcn). In contrast, with previous reports for TiFeNbO6 we find no evidence of relaxor ferroelectric behaviour with all three materials instead exhibiting Maxwell-Wagner-like relaxation. Impedance spectroscopy confirms semiconductor behaviour. Magnetically, all three materials can be described by infinite irregular antiferromagnetic S = 5/2 chains with weak ferromagnetism below 10 K. These chains have random directions of propagation between nearest Fe-Fe neighbours consistent with the disordered nature of these materials. We observed a negative imaginary part of the ac susceptibility related to the defect magnetic topology.

Structural, Morphological, Optical, and Magnetic Properties of NiO-added NiCo2O4 Electrode Materials Synthesized by Sol-Gel, Co-Precipitation and Ultrasonication Methods and their Electrochemical Supercapacitor Response

In this study, NiO-added NiCo2O4 composite samples were prepared using three distinct synthesis methods to study the impact of synthesis technique and NiO addition on the electrochemical performance of NiCo2O4. The chosen methods, sol-gel, co-precipitation, and ultrasonication, represent a range of approaches that yield different particle structures and morphologies. The structural and morphological studies of composite samples were investigated using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM), respectively. XRD analysis revealed the crystalline composition, revealing the presence of two distinct phases: NiO and NiCo2O4. The Rietveld analysis of the composite samples supports the dual phases in the samples. FESEM analysis confirms the change in size and shape of the particles with the synthesis procedure. Optical properties, measured via UV-visible absorbance spectra, demonstrated that the energy gap varied with the synthesis method. The sol-gel samples exhibited the highest energy gap at 2.20 eV. The magnetic properties were measured using the vibration sample magnetometer (VSM), and the results confirm that the synthesis procedure influences magnetic loops and coercivity. The electrochemical performance of the samples in a 3 M potassium hydroxide electrolyte revealed that the co-precipitation method produced the highest capacitance of 398 Fg-1 at a 10 mV/s sweep rate, indicating superior energy storage capacity compared to pure NiCo2O4. Adding NiO phase to the NiCo2O4 matrix is believed to enhance electrochemical performance by creating additional charge at the grain boundaries, leading to a synergistic effect and improved electron and ion transport. The exceptional electrochemical performance of these composite materials suggests that the synthesis methods and the addition of NiO play a critical role in determining the overall efficiency and applicability of battery-type supercapacitors. These findings pave the way for further research into optimizing synthesis parameters to enhance energy storage capacity and inspire the development of advanced spinel metal oxide composite electrodes for supercapacitors and other energy storage applications.

Excellent dielectric response and microwave absorption in magnetic field-induced magnetic ordered structures

Weak interactions prevent the magnetic particles from achieving excellent electromagnetic wave absorption (EMA) at a low filler loading (FL). The construction of one-dimensional magnetic metal fibers (1D-MMFs) contributes to the formation of an electromagnetic (EM) coupling network, enhancing EM properties at a low FL. However, precisely controlling the length of 1D-MMFs to regulate permittivity at low FL poses a challenge. Herein, a novel magnetic field-assisted growth strategy was used to fabricate Co-based fibers with adjustable permittivity and aspect ratios. With a variety of FL changes, centimeter-level Co long fibers (Co-lf) consistently exhibited higher permittivity than Co particles and Co short fibers due to the enhancement of the effective EM coupling. The Co-lf exhibits excellent EMA performance (-54.85 dB, 5.8 GHz) at 10 wt.% FL. Meanwhile, heterogeneous interfaces were introduced to increase the interfacial polarization through a fine phosphorylation design, resulting in elevated EMA performances (-51.50 dB, 6.6 GHz) at 10 wt.% FL for Co2P/Co long fibers. This study improves the orderliness of the particle arrangement by regulating the length of 1D-MMFs, which affects the behavior of electrons inside the fibers, providing a new perspective for improving the EMA properties of magnetic materials at a low FL.

Design and Analysis of New Type of Magnetically Controlled Reactor

In recent years, various new types of magnetic materials have emerged, especially in the field of nanotechnology. The application of material composite technology has formed a new type of dual-phase composite magnetic material. Under the control of an external magnetic field, the material can achieve functional conversion between the hard magnetic phase and the soft magnetic phase, with magnetic permeability, non-magnetic permeability, and excitation ability. In this paper, it is proposed to use this material as the basic material for the magnetic state control of the reactor core, break through the bondage of the traditional reactor core to the performance of the controllable reactor, and innovatively form a new type of reactor structure. By adding a detection and control system, according to the working state of the power grid, the function conversion of the nano adjustable magnetic material is effectively adjusted to realize the automatic adjustment of the magnetic state of the reactor. Firstly, the preparation and material properties of dual-phase composite magnetic materials were studied. The design and preparation process from magnetic powder to bulk magnet were given, and the magnetic properties were measured. Secondly, a new 380 V/100 kVar magnetically controlled reactor was designed by using dual-phase composite magnetic material to form a composite core of magnetically controlled reactor on silicon steel sheet. The simulation analysis of electromagnetic characteristics and volt-ampere characteristics was carried out to verify the correctness of the proposed scheme.

Meter‐Scale Distance Manipulation of Diverse Objects with Jet‐Induced Airflow Field

In nature, wind can transport objects of diverse shapes and materials over long distances spanning meters or beyond. In contrast, most noncontact manipulation methods are effective only over centimeter‐scale distances and require the manipulated objects to have specific magnetic, electrical, or other material properties and shapes. Herein, a meter‐scale distance manipulation method is presented for controlling the motion of objects of diverse shapes and materials on a plane surface using a jet‐induced airflow field. The airflow field is varied by controlling the direction of a single air jet projected onto a surface based on the positions of objects to steer the objects to follow desired trajectories up to 2.7 m away. A wide variety of objects can be automatically manipulated, from regularly shaped polystyrene hemispheres and sticks to irregularly shaped cotton wads and face masks as well as deformable tissue papers and plastic bags. The method is also robust, effectively manipulating objects under challenging conditions, e.g., external airflow disturbances, surface obstacles, and air–water interface. Finally, three application cases are demonstrated: collecting diverse objects into a target receptacle, hooking and retrieving heavy objects with a tethered mobile agent, and closing an electrical circuit with an untethered soft agent.

Tuning magnetic and optical properties in Mn x Zn1−x PS3 single crystals by the alloying composition

The exploration of two-dimensional (2D) antiferromagnetic (AFM) materials has shown great promise and interest in tuning the magnetic and electronic properties as well as studying magneto-optical effects. The current work investigates the control of magneto-optical interactions in alloyed Mn x Zn1−x PS3 lamellar semiconductor single crystals, with the Mn/Zn ratio regulating the coupling strength. Magnetic susceptibility results show a retention of AFM order followed by a decrease in Néel temperatures down to ∼40% Mn concentration, below which a paramagnetic behavior is observed. Absorption measurements reveal an increase in bandgap energy with higher Zn(II) concentration, and the presence of Mn(II) d-d transition below the absorption edge. DFT + U approach qualitatively explained the origin and the position of the experimentally observed mid band-gap states in pure MnPS3, and corresponding peaks visible in the alloyed systems Mn x Zn1‒x PS3. Accordingly, emission at 1.3 eV in all alloyed compounds results from recombination from a 4T1g Mn(II) excited state to a hybrid p-d state at the valence band. Most significant, temperature-dependent photoluminescence (PL) intensity trends demonstrate strong magneto-optical coupling in compositions with x > 0.65. This study underscores the potential of tailored alloy compositions as a means to control magnetic and optical properties in 2D materials, paving the way for advances in spin-based technologies.

Dynamic and controlled stretching of macroscopic crystalline membranes towards unprecedented levels

Imposing and controlling strain in materials such as semiconductors or ferroelectrics is a promising way to obtain new or enhance existing properties. Although the field of strain engineering has seen a rapid expansion over the last two decades, straining semiconductor membranes over large areas remains a challenge. A generic way of tuning strain and hence band structure and electric or magnetic properties of any crystalline material can be obtained by compression of a composite structure involving poorly compressible elastomers. Mechanically similar to the principle of a hydraulic press, this work proposes a device and describes analytically a methodology to easily strain macroscopic membranes up to unprecedented values. Using in-situ X-ray diffraction and Raman spectroscopy, we tuned the biaxial strain in silicon membranes up to a value of 2.1 %, paving the way for new studies in the field of strain related physics, from semiconductors to perovskite oxide multiferroics.

Magnetic Properties of Fe-Si Electrical Steel after Laser Scribing

Improvement of magnetic properties of electrical steel can be achieved by reduction the size of magnetic domains. The application of local stresses through laser scribing leads to reduced core losses. In order to determine the effect of laser refinement conditions of magnetic domains on the properties of the soft magnetic material, four samples with a thickness 0.23 mm were refined. The refinement of each sample was carried out using different line energies of the laser beam. Estimation of the magnetic domain size was performed using the Jeffries method, the magnetic viewer was used to reveal the domain structure. The measurement of the magnetic properties was performed at a frequency of 50 Hz and an induction of 1.5 T. The analyzed results presented in this work indicate impact of laser refining on magnetic properties of grain oriented electrical steel depending on used laser beam energy.

Giant Modulation of Refractive Index from Picoscale Atomic Displacements.

It is shown that structural disorder-in the form of anisotropic, picoscale atomic displacements-modulates the refractive index tensor and results in the giant optical anisotropy observed in BaTiS3, a quasi-1D hexagonal chalcogenide. Single-crystal X-ray diffraction studies reveal the presence of antipolar displacements of Ti atoms within adjacent TiS6 chains along the c-axis, and threefold degenerate Ti displacements in the a-b plane. 47/49Ti solid-state NMR provides additional evidence for those Ti displacements in the form of a three-horned NMR lineshape resulting from a low symmetry local environment around Ti atoms. Scanning transmission electron microscopy is used to directly observe the globally disordered Ti a-b plane displacements and find them to be ordered locally over a few unit cells. First-principles calculations show that the Ti a-b plane displacements selectively reduce the refractive index along the ab-plane, while having minimal impact on the refractive index along the chain direction, thus resulting in a giant enhancement in the optical anisotropy. By showing a strong connection between structural disorder with picoscale displacements and the optical response in BaTiS3, this study opens a pathway for designing optical materials with high refractive index and functionalities such as large optical anisotropy and nonlinearity.

Fabrication and Characterization of a Magnetic 3D‐printed Microactuator

AbstractConventional MEMS microactuators have, in recent years, been complemented by 3D‐printed actuatable microstructures fabricated via two‐Photon‐Polymerization (2PP). Herein, a novel compact 3D‐printed magnetically actuatable microactuator with a diameter of 500µm is demonstrated, originally designed for micro‐optical systems. It is fabricated by incorporating a composite of NdFeB microparticles and epoxy resin into a designated reservoir of the printed mechanical structure within a simple post‐processing step. The microactuator structure features mechanical springs, allowing for continuous positioning with large displacement. Mechanical studies by nanoindentation of IP‐S bulk structures reveal a viscoelastic material behavior, described by a two‐element General Kelvin‐Voigt viscoelasticity model. The obtained material parameters are then used to simulate and characterize the spring behavior of the microactuator. Actuation experiments are conducted using an external microcoil. The actuator displacement is measured for triangular current pulses with a peak current of 106 mA and durations of 1 to 100 s, resulting in displacements of 69.1 to 88.9 µm. Hysteretic behavior of the actuator is observed, attributable to viscoelasticity and magnetic properties of the core material. Numerical simulations of the experiment demonstrate this behavior as well. On‐the‐fly demagnetization and the implementation of closed‐loop control allow for both high repeatability and precise positioning.

Room temperature photosensitive ferromagnetic semiconductor using MoS2

Two-dimensional semiconductors, including transition metal dichalcogenides (TMDs), are of interest in electronics and photonics but remain nonmagnetic in their intrinsic form. Atomic modulation using physical and chemical ways is an effective means to control the physical properties such as magnetic and electrical properties of two-dimensional materials which can be controlled by irradiation. Here we treat mechanically exfoliated MoS2 with a helium ion beam, which exhibits semiconducting and ferromagnetic ordering at room temperature, while Monte Carlo simulations and theoretical calculations confirmed that the control of nanoholes result in the presence of magnetism. In addition, the irradiation results of multilayer MoS2 show that the magnetic moment increases with the increase of 10 layers. The conductivity remains virtually unchanged before and after being treated by a helium ion beam. The treated MoS2 spintronic device displays the switch of ‘on/off” under the light, magnetic field, and/or electric field, which means 2D photosensitive ferromagnetic semiconductor functions are successfully demonstrated at room temperature.

Magnetic behaviour of a mixed-spin ising model on a two-dimensional square-octagon lattice in a dynamic magnetic field

The magnetic behaviours of a two-dimensional square-octagon lattice with mixed spin 5/2 and spin 1 magnetic atoms are investigated in a dynamic magnetic field using effective field theory with correlations. We studied the effects of exchange coupling, anisotropy, oscillating magnetic fields, and temperature on the dynamic magnetic and thermodynamic properties of the square-octagon lattice. The dynamic magnetisation, order parameters, susceptibility, internal energy, and phase diagram of the system were obtained. These results significantly contribute to our understanding of the dynamic magnetic properties of two-dimensional materials. The ability to manipulate and control magnetic behaviour in two dimensions holds promise for the creation of more efficient and versatile devices.

GPTArticleExtractor: An automated workflow for magnetic material database construction

A comprehensive database of magnetic materials is valuable for researching the properties of magnetic materials and discovering new ones. This article introduces a novel workflow that leverages large language models for extracting key information from scientific literature. From 22,120 articles in the Journal of Magnetism and Magnetic Materials, a database containing 2,035 magnetic materials was automatically generated, with ferromagnetic materials constituting 76% of the total. Each entry in the database includes the material’s chemical compounds, as well as related structures (space group, crystal structure) and magnetic temperatures (Curie, Néel, and other transitional temperatures). To ensure data accuracy, we meticulously compared each entry in the database against the original literature, verifying the precision and reliability of each entry.

Investigation of mechanical properties of graphene-CNT reinforced nickel metal matrix nanocomposite structure

Nickel is a metal widely used in many industrial applications, but despite its superior properties, it also has some shortcomings. Carbon-based structures can be important reinforcement elements in improving the properties of metals. By providing a balance between the high corrosion resistance, high electrical conductivity and good magnetic properties of the nickel material and the lightness and high strength of carbon-based structures, a material with advanced properties can be obtained. Therefore, in this study, a new Nickel-Carbon nanostructure supported by a covalently bonded graphene-carbon nanotube (CNT) skeleton structure is presented. Additionally, three material designs with different geometric dimensions (Ni-G-CNT(5,5), Ni-G-CNT(10,10) and Ni-G-CNT(15,15)) were designed to determine the mechanical properties and properties of the structures in all directions. is to investigate the underlying deformation mechanisms. According to the results, it was observed that G-CNT structures increased the tensile and compressive behavior of the Ni structure in the CNT direction. For tensile loading in the CNT direction, as the CNT diameter decreases, the elastic modulus of the hybrid structures increases, while the maximum stress values are independent of the CNT diameter. As the CNT diameter increases, the ductility of the structures increases. In terms of compressive strength, it has been observed that in the linear region, as the CNT diameter increases, the strength generally increases and in the condensation region, it exhibits better compressive strength. With this study, an anisotropic nanostructure that is lighter and can exhibit higher tensile strength compared to the Ni structure is presented.

Effect of divalent metal ions substitution on the magnetic properties of Ba3Co2-xMexFe24O41 (Me = Zn2+, Ni2+) hexagonal ferrites

With the high-frequency development of communication technology, traditional communication materials have been difficult to meet the application requirements. Z-type hexagonal ferrite materials are widely used as good magnetic dielectric materials in high-frequency communication applications due to their high cut-off frequency and magnetodielectric properties. However, the high-frequency magnetodielectric properties need to be further improved, so the magnetic properties of the divalent metal ion-substituted Co2Z hexagonal ferrite materials are studied, and the anisotropy is calculated according to its static magnetic properties in this paper. A series of the ferrites Ba3Co2-xMexFe24O41(Me = Zn2+, Ni2+, where x = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0) were prepared by high-energy ball milling and sintering at 1260℃ for 3 h. The structural and magnetic properties of the samples were investigated using X-ray diffraction, vibrating sample magnetometer, and vector network analyzer. The studies indicated that the magnetic Ni2+ ions substitution increases the cutoff frequency, and the nonmagnetic Zn2+ ions substitution plays a positive role in increasing the magnetic permeability. Particularly, the Ba3Co1.6Ni0.4Fe24O41 and Ba3Co1.2Zn0.8Fe24O41 both have equal permeability and permittivity about 9 and 12, and their cutoff frequency exceed 2 GHz and 1 GHz, respectively. At the same time, these isomagnetic dielectric materials also have low loss, which will have great application potential in microstrip antennas.

Multifunctional Ce+3 doped nickel-cobalt mixed ferrites via co-precipitation method for photocatalytic and antibacterial activity

The overuse of industrial dyes and anti-bacterial drugs are destroying fresh water reservoirs and making bacteria more resistant, respectively. To sort out these problems, we have synthesized Cerium doped Nickel-Cobalt mixed ferrites (Ce-@NCMF) with chemical composition [Ni0.4Co0.6CexFe2-xO4 (where x = 0.00, 0.10, 0.15, 0.20 and 0.25)] via co-precipitation method. Influence of cerium doping on the structural, optical, electrical, magnetic, photocatalytic and anti-bacterial properties of Ce-@NCMF studied. Powder x-ray diffraction analysis (PXRD) confirmed the synthesis of Ce-@NCMF. Decrease of crystallite size from 29.71 to 24.95 nm was observed with increase in dopant concentration. Tauc’s plot indicated the decrease of energy bandgap from 2.10 to 1.89 eV with increase in dopant concentration, which revealed the absorption of light in visible region to generate electron–hole pairs for photocatalytic applications. FTIR spectra indicated the presence of M-O bonds as major functional group present in Ce-@NCMF. Electrical properties demonstrated the prominent increase of electrical conductivity with increase of Ce-doping. VSM analysis was performed to analyse the magnetic properties of materials and showed prominent decrease in saturation magnetization value from 84.66 to 19.85 emu g−1. Owing to optical bandgap in the visible region, all the synthesized samples were evaluated for their photocatalytic potential for the degradation of methylene blue. Ce-@NCMF at x = 25% dopant value showed maximum degradation efficiency (95%) under sunlight irradiation of 90 min. Kinetic studies of dye degradation followed pseudo-1st order kinetics with maximum rate constant (k) value of 2.78×10−2 min−1. Antibacterial activity results showed the bioactive nature of Ce-@NCMF against all strains of bacteria in consistent with the crystallite size of samples. Smallest crystallite size Ce-@NCMF were found most active against gram-negative bacterial strains.