Spin Hall conductivity (SHC) of W_100-xSi_x alloys in the A15 structure is investigated using first-principles calculations. Various concentrations of x (0, 3.125, 6.25, 12.5, and 25 %) are calculated for different configurations. Formation energy is used to investigate structural stability, where the substitution Si into bcc sites is energetically favorable. For each x, the thermodynamic average of SHC (σ_xy) is taken. Notably, at x = 3.125 %, σ_xy= -1306 S/cm is the largest among W_100-xSi_x alloys, which is enhanced by 59 % over β-W of σ_xy = -818 S/cm. The enhanced SHC is explained by negative Berry curvature.

This paper establishes a simple analytical formula-based model of magnetization of single-domain magnetic nanoparticles, taking into account the effect of a demagnetizing field. This makes it easier to calculate magnetic induction intensity for magnetic nanoparticles. The magnetization model is used to simulate the magnetic properties of Fe-Co-Ni alloy nanoparticles under various conditions. The results show that the demagnetization field generated by magnetic nanoparticles in an external magnetic field reaches a peak value around 10 nm and decreases as temperature rises. The simplified magnetization model of single-domain magnetic nanoparticles could provide the theoretical basis for single-molecule magnetic immunoassay.

Using first principles calculations, we explore the biaxial tensile strain-dependent magnetic properties of monolayer and bilayer Fe₃GaTe₂. Like in the pristine structure, the ferromagnetic ground state is obtained under biaxial tensile strain. Besides, we obtain out of plane magnetic anisotropy in both monolayer and bilayer Fe₃GaTe₂ structures, and the magnetic anisotropy shows increasing tendency with strain. The Curie temperature is suppressed under tensile strain regardless of the enhancement of magnetic anisotropy energy. Both anomalous Hall conductivity and anomalous Nernst conductivity in the bilayer show oscillating behavior under biaxial tensile strain, while the monolayer exhibits less sensitive but still oscillates.

In order to obtain the detection efficiency according to the distance around the detector, the total energy peak efficiency was used, and the grid mapping method was used to investigate axis-symmetry. The detector was measured at 0.5 cm intervals up to 5 cm in the x, z, direction, and 5.5 cm in the y direction. The efficiency of the cylinder beaker and marinelli beakers at the center of the ¹³⁴Cs 604 keV detector was compared with the efficiency of the mapping method. For cylinder beakers, the efficiency was 0.0412 ± 0.002, and the efficiency by mapping was 0.040 ± 0.001, which was consistent within 3 % of the uncertainty range. For Marinelli beakers, the efficiency was 0.0242 ± 0.002 mapping efficiency was 0.0248 ± 0.0013. It was confirmed that precise measurement of radioactive sources with volume was possible when measured at each point around the detector.

The electron magnetic resonance (EMR) of the paramagnetic Cr³⁺ ion in an alexandrite single crystal (BeAl₂O₄:Cr³⁺) has been investigated. The resonance fields of Cr³⁺ impurity ion measured with a Q-band electron magnetic resonance spectrometer were obtained under angular variation along crystallographic ab-, bc-, and ca-planes. The spectroscopic splitting parameters g_ij and the 2^nd order zero-field splitting parameters D_ij of the Cr³⁺(II)-center at Al³⁺(II) site in an alexandrite single crystal with mirror symmetry are obtained by using the effective spin Hamiltonian. The EMR parameters and rotation patterns show that the actual local site symmetry of the Cr³⁺ ion is monoclinic. The number of magnetic resonance signals and crystal structures were compared and analyzed in detail where impurity ions in a single crystal are replaced. It turns out that the Cr³⁺ impurity ions in an alexandrite single crystal occupies the Al³⁺(II) site without charge compensation instead of the Be²⁺ and Al³⁺(I) sites.

This article aims to propose and analyze a power factor increased modular stator dual-permanent-magnet-excited vernier (DPMEV) machine. Currently, the DPMEV machines suffer from a low power factor due to significant amplitude of armature non-working harmonics. With the modular stator design, the magnetic circuit of low-order non-working harmonics is interrupted, effectively reducing its amplitude without compromising working harmonics. Consequently, the proposed DPMEV machine achieves a notable improvement in power factor, increasing from 0.5 to 0.69 under rated conditions compared to non-modular machines. Firstly, the topology and working principle of proposed machine are introduced. Then, air gap flux density model is established for investigating the mechanism of power factor improvement. Furthermore, a comprehensive analysis is conducted using finite element analysis to study the influence of critical dimension parameters on the power factor, including PM thickness, PM pole arc and modulated pole angle. Lastly, a modular stator DPMEV prototype is manufactured and tested for validation. The experiments results closely align with the finite element analysis.

This paper addresses the electromagnetic field characteristic analysis of a surface-mounted permanent magnet synchronous motor (SPMSM) and an interior permanent magnet synchronous motor (IPMSM) according to driving methods, which are blushless AC mode and blushless DC mode. For the reasonable comparison, the IPMSM is newly optimized based on the design of experiment to have very similar equivalent circuit parameters and identical machine size compared to the conventional SPMSM. Based on finite element method, various electromagnetic field characteristics, such are flux density, induced voltage and cogging torque, are comparatively analyzed, and the finally designed machine is manufactured for their experimental verification. With the manufactured machine and inverters, phase current waveforms according to the driving methods are measured, and the influence of their separated harmonics on motor performance is comparatively investigated.

To enhance the comprehensive utilization of high-abundance La and Ce, misch metal (MM)–Fe–B magnets have become the research focus. Herein, considerable differences were observed in the magnetic properties and microstructure of rare earth (RE)–Fe–B ribbons prepared using natural or artificial MM with varying La/Ce ratios. With increasing La content, the total magnetic properties of the involved thin RE–Fe–B strip deteriorated; meanwhile, the MM–Fe–B ribbon exhibited high coercivity and maximum magnetic-energy-product values of 9.2 kOe and 9.28 MGOe, respectively. Notably, the La utilization rate increased to 28 wt.% (La/TRE). A conspicuous heterogeneous distribution of RE elements and dual hard-magnetic phases in the MM–Fe–B ribbon were noted based on transmission electron microscopy microanalysis and first-principles calculations, unlike for the (Ce, Pr, Nd)–Fe–B ribbon. Henkel plot measurements confirmed a strong exchange-coupling interaction within the MM–Fe–B ribbon, attributed to the spontaneous formation of dual hard-magnetic main phases—La–Ce-poor and La–Ce-rich.

Aiming at the problem of serious temperature rise in the power transmission process of the traditional magnetorheological fluid transmission device, a counter-roller structure is proposed. This paper analyzes the magnetic field characteristics of counter-roller magnetorheological fluid drives with different coil arrangements. Based on the theory of electromagnetism, the magnetic field design of the counter-roller magnetorheological transmission device was carried out. The magnetic field simulation results show that under the condition the current is 1.5A and the working gap is 1.5 mm, the magnetic induction intensity of the working area under different arrangements can reach more than 0.5A, which meets the working requirements. The working magnetic field intensity increases with the increase of current, decreases with the increase of the working gap, and increases with the increase of material permeability. The average magnetic induction intensity under the radial coil arrangement is larger than that under the circumferential coil arrangement. The combined use of circumferential coil and radial coil arrangement can improve the magnetic field distribution characteristics in the working area of the roller drive, thus further improving its transmission characteristics.

In this experiment, quenched Fe₇₃Ga_27-xAl_x and (Fe₇₃Ga_27-xAl_x)_99.8Tb_0.2 alloys (x=0, 1 , 2, 3, 4, 5) were respectively prepared, and the effects of 0.2 at% Tb doping on the microstructure and magnetic properties of Fe₇₃Ga_27-xAl_x alloys were studied. The results show that the phase structure of Fe₇₃Ga_27-xAl_x and (Fe₇₃Ga_27-xAl_x)_99.8Tb_0.2 alloys are mainly composed of A2 phase, but (Fe₇₃Ga_27-xAl_x)_99.8Tb_0.2 alloys also contain a small quantity of Tb₂Fe₁₇ phase. After Tb doping, the lattice constant of alloys is descended, altering the microstructure of alloys, and the orientation of (Fe₇₃Ga₂₇)_99.8Tb_0.2 and (Fe₇₃Ga₂₅Al₂)_99.8Tb_0.2 a lloys a long the crystal direction [100] is increased saliently. The Al element in (Fe₇₃Ga_27-xAl_x)_99.8Tb_0.2 alloy exists in the form of deposited phase, and Tb₂Fe₁₇ phase is formed at grain boundaries after Tb doping, thus improving the magnetostrictive property of alloys. The λ_∥ and Vickers hardness of Fe₇₃Ga_27-xAl_x alloys are in the range of 52-64×10^-6 and 316.13-328.68 HV, separately. After Tb element doping, the λ_∥ and Vickers hardness of the alloy reach the maximum 88×10^-6 and 408.49 HV at x=2 at%, which is individually increased by 69.23 % and 29.21 % compared with Fe₇₃Ga₂₅Al₂ alloy. And its Hc keeps low, which can reduce magnetization powers and losses. Therefore, (Fe₇₃Ga_27-xAl_x)_99.8Tb_0.2 alloy gives consideration to the excellent magnetic properties and high Vickers hardness, having the most practical production value in the two series of alloys.

The heterogeneity of images generated by positron emission tomography (PET)/magnetic resonance (MR) imaging systems significantly compromises diagnostic accuracy in the medical field. This study developed and refined a bias field correction strategy leveraging a gray-level co-occurrence matrix (GLCM) to enhance the uniformity of MR images within a PET/MR fusion imaging framework. We utilized a spherical phantom imbued with solutions of NaCl and NaCl+NiSO₄ for image acquisition, employing T₂-weighted turbo spin echo (TSE) and half-Fourier-acquired single-shot turbo spin echo techniques. The algorithm introduced for uniformity enhancement fine-tunes the contrast and energy metrics of the GLCM to identify an optimal lambda value. The application of this algorithm to MR images resulted in a marked improvement in percentage image uniformity (PIU), displaying superior characteristics relative to the uncorrected images. Specifically, the application of our algorithm to phantom images prepared with NaCl + NiSO₄ and using the T₂-weighted TSE technique yielded an average PIU of 97.72 %. In summary, we modeled a GLCM-based algorithm that can correct uniformity in MR images and confirmed the applicability of the proposed method in PET/MR systems.

This study employed nanolithography to create geometric defects in magnetic components. Nanolithography is a technique that utilizes an AFM probe to exert pressure on the sample surface and follow specific paths, enabling the creation of two-dimensional patterns on a thin film. We fabricated a permalloy disk using electron beam lithography and then used multiple scrapes to remove an area of devices. Subsequently, each iteration was observed using a MOKE microscope to analyze its impact on magnetic reversal behavior. The magnetic hysteresis loops show no significant changes during small edge area engraving for a circular disk. As the removed edge area increases, the appearance time of vortices decreases. In addition, we fabricated a magnetic wire with an injection pad and created notches on the wire using electron beam lithography and nanolithography, respectively. We investigated the depinning behavior of magnetic domain walls behind these notches. Experimental data identify significant differences in depinning fields for defects produced by the two distinct processes.

Giant magnetoimpedance (GMI) sensors are typically used for the detection of weak biomagnetic fields. Existing methods for increasing the linear operating range of giant magnetoimpedance (GMI) sensors require additional feedback coils, increase the size of the GMI sensors. In this study, we extended the dynamic range of a pulse excitation-driven GMI sensor by implementing single-coil feedback to an off-diagonal GMI sensor. We employed a high-pass filter to effectively separate the sensor's output waveform from the feedback current. Investigating the optimum feedback gain for high sensitivity and dynamic range allowed us to achieve a dynamic range of 130 dB without increasing the noise floor.