We report here the ferromagnetic-layer thickness dependence of the creep-scaling behavior in Pt/Co single interface films. By means of an in-vacuum magneto-optical Kerr effect microscope, the magnetization dynamics were observed in the films with different Co layer thickness. From the clear domain-wall creep-scaling behaviors, the creep-scaling constant was determined and analyzed with respect to the Co layer thickness. The thickness dependence of the creep-scaling constant manifests the formation of a ferromagnetic dead layer, the thickness of which is roughly about one monoatomic layer. By excluding the dead-layer thickness, it becomes clear that the effective magnetic layer thickness is proportional to the creep-scaling constant, confirming the validity of the creep-scaling theory.

We investigated the magnetic properties of SrRuO₃ epitaxial thin film synthesized by using pulsed laser deposition on KTaO₃ (001) substrate. X-ray reciprocal space mapping scans showed clear peaks demonstrating high quality, tensile strain with increased unitcell volume, and relaxed growth behavior. Magnetization data shows that the magnetization of the SrRuO₃ film with magnetic field along the in-plane direction was larger than one with magnetic field along surface-normal direction.

We report in this work the effects of the Polyvinylpyrrolidone (PVP) concentration on the solvothermal synthesis of Fe₃O₄ nanocluster with different PVP concentrations such as 5 mg/ml, 10 mg/ml, and 25 mg/ml. The effect of the PVP on the structural, microstructural, and magnetic properties was analyzed using different techniques. XRD patterns showed the crystallization of all samples in the cubic structure with an average crystallite size smaller than 10 nm. Homogeneous dispersion of the nanoparticles was shown for small concentrations of PVP, while the aggregation of the nanoparticles was observed for higher concentrations leading to the formation of uniform nanoclusters with an average size around 167 nm for a PVP concentration of 25 mg/ml. A soft ferromagnetic behavior was found for all prepared samples with a saturation magnetization of about 54.75 emu/g obtained for Fe₃O₄ nanoparticles with 10 mg/ml of PVP.

ε-Fe₂O₃ has received attention with particular interest because of its large coercive field at room temperature, high-frequency millimeter-wave absorption, and the coupling of its magnetic and dielectric properties. This work investigated the effect of heat treatment on the formation of ε-Fe₂O₃/SiO₂ composites fabricated using reverse-micelle and sol-gel methods. The heating process was performed at various temperatures to figure out the optimal conditions for acquisition of the ε-Fe₂O₃ phase, which exhibits the largest coercive field among the Fe oxides. The sample treated at 1,075 ℃ had the highest percentage of ε-Fe₂O₃ phase, with a coercivity (H_C) of 21.57 kOe measured at room temperature that reached a maximum of 23.7 kOe at 230 K. The measurement of the magnetization-temperature (M-T) curve for this sample also reveals the characteristic magnetic transition associated with ε-Fe₂O₃ within the temperature range of 40-150 K. The crystal structure of ε-Fe₂O₃ was confirmed using X-ray powder diffraction. Transmission electron micrographs revealed a broad size distribution of iron oxide nanoparticles ranging from 12 to 22 nm. The findings indicate that ε-Fe₂O₃ is a promising candidate with high electromagnetic-wave absorption capacity that is appropriate for high-speed wireless communication applications.

Iron-silicon thin films used as a single layer or in sandwich structures are currently regarded as a promising candidate in high magnetic sensors. A detailed understanding of magnetization dynamics in such thin films is of great interest. In this work, we only focused on modeling the magnetization reversal. Numerical solution to the nonlinear Landau-Lifshitz-Gilbert (LLG) equation can be used to conduct the study. With the help of our developed Matlab code, the simulations were carried out. External field strength, damping parameter and temperature all have an impact on the speed of the magnetization reversal. The validation of our computations is achieved via a separate simulation. It relates to the solution of the standard problem proposed by the micromagnetic Modeling Activity Group (μMAG). The results are in agreement with the ones presented in the National Institute of Standards and Technology (NIST) website.

This study aims to examine the effect of various composition ratios on the exchange spring effect of strontium ferrite (SrFe₁₂O₁₉)/cobalt ferrite (CoFe₂O₄) nanocomposite magnets. Nanoparticles of hexagonal hard phase SrFe₁₂O₁₉ and spinel soft phase CoFe₂O₄ were each prepared through mechanical alloying and high-power ultrasonic irradiation processes. Furthermore, the constituent of the hard-soft particles was weighed based on its ratios and the mixture was homogenized under a sonicator-type Qsonica at a frequency of 20 kHz for an hour. The bulk composite samples were obtained in cylindrical pellets form through compaction of mixture powders at 5000 kg/cm², followed by sintering at 1200 ℃. The exchange spring effect enhanced the magnetic properties, surpassing the normal limit for non-interacting magnetic particles due to enhanced grain interactions. The results showed that the degree of property enhancement depended on the various composition ratios and microstructure of the composite magnets. The magnetization of saturation (M_s) of the samples increased compared to a single SrFe₁₂O₁₉. Furthermore, the highest coercivity (H_c) and product energy maximum (BH)_max values were observed in the sample which had mass ratios of SHF:COF of 85:15 with coded S80C20. The occurrence of exchange spring effects was observed in material characterized by a microstructure consisting of a hard-magnetic phase with elevated magnetocrystalline anisotropy and saturation magnetization values, along with a soft magnetic phase exhibiting high saturation magnetization value.

This paper presents how to select the proper slot and pole combination (SPC) and reasonable rotor topologies for an interior permanent-magnet (IPM) machine. Firstly, the selection principle of SPC is reported, and some electromagnet performances, including winding factor, stator space magneto-motive force (MMF) harmonics, radial force harmonics, and cogging torque, are analyzed and compared. Secondly, four PM rotor topologies are designed and discussed, including surface permanent-magnet (SPM), spoke type, V-shape, and multi-layer reluctance (MR) type. Their performances, such as back-EMFs, torque, and ripple and flux-weakening capability, are thoroughly analyzed and compared by the finite-element method (FEM). Finally, a 27-slot and 8-pole V-shape IPM machine is selected and designed optimally, which offers high power/torque density, high efficiency, and less torque ripple. In order to ensure the reliability of its rotor mechanical strength, the equivalent stress and deformation are analyzed by ANASY. Besides, its d-q axis mathematical model is built to verify its performance further. Then experiments on the prototypes are carried out for validation.

This paper presents an improved T-shape linear permanent magnet machine (T-LPMM) based on a traditional surface-mounted linear permanent magnet machine (SM-LPMM). The proposed topological structure aims to protect the surface of the permanent magnet from corrosion and enhance the rigidity against make high-frequency vibration. Firstly, the slotless magnetic field is predicted using finite-element method (FEM) with automatic scripting in MATLAB to consider the inset T-shape structure of PM. Then, the Schwarz-Christoffel (SC) mapping is adopted to calculate the slot effect. Afterward, a subdomain (SD) model is established to analyze the armature reaction, and Taguchi method is employed for optimization purposes. The optimized result is verified by FEM, and a comparison experiment is conducted between T-LPMM and SM-LPMM. The experimental demonstrate superior electromagnetic output performance of the proposed T-LPMM.

At present, most of the seat suspensions of heavy-duty trucks use passive suspension and active suspension. The passive suspension has gradually failed to meet people's needs in terms of vibration reduction performance, and the active suspension will consume too much energy. In this paper, a stepped by-pass valve magnetorheological semi-active suspension based on fuzzy PID control is proposed. The Simulink is used to simulate the system. In the case of sinusoidal excitation, the results show that this semi-active suspension reduces the vertical acceleration by 44.36%, the dynamic deflection of the suspension by 29.63% and the dynamic deformation of the tire by 43.78% compared with the passive suspension. Under the condition of C-level road surface input, the vertical acceleration of the suspension is reduced by 35.14%, the dynamic deflection of the suspension is reduced by 31.93%, and the dynamic deformation of the tire is reduced by 27.65%.

Considerable attention has been given to controlling magnetic anisotropy for future flexible spintronic devices because the magnetization behavior of magnetic thin film and device changes with the bending stress, which is known as the inverse-magnetostriction effect. The net magnetic anisotropy resulting from the fabrication process plays a significant role in determining the working functions for magnetic field applications. In this study, the variation of intrinsic magnetic anisotropy in permalloy thin films was investigated depending on the dcmagnetron sputtering position. The randomly formed magnetic easy-axis was finally controlled by the application of magnetic field during the sample deposition.

This paper studies magnetic field control and velocity-activated magnetorheological shear thickening fluid (MR-STF). High-concentration STF is composed of nano-sized silica particles suspended in a solvent polyethylene glycol (PEG), and then micron-sized carbonyl iron particles of different mass fractions are added to the STF to manufacture different MR-STF. The rheometer is used to study the viscoelasticity of all four samples. The correlation between dynamic behavior and shear rate, angular frequency, and external magnetic field is studied and discussed. In the lower angular frequency range, the loss modulus is slightly larger than the storage modulus, and MR-STF behaves as a viscoelastic state. After the critical angular frequency, the storage modulus decreases sharply, well below the loss modulus. MR-STF appears in a viscous state and a liquid state. With the start of external field excitation, MR-STF is more inclined to MRF. Finally, the apparent viscosity and shear rate of MR-STF are fitted. The results show that with the increase of magnetic induction strength, the plastic viscosity coefficient of MR fluid increases, the flow characteristic index decreases, and the shear thinning effect becomes more significant.

Large latent heat is produced in the stress-induced martensitic phase transition process of Ni-Mn-Ca-based materials, i.e., elastocaloric effect. That makes such materials show tremendous potential for solid-state refrigeration which is identified as one of the most promising non-vapor-compression cooling devices. However, the still low refrigeration ability of these materials restricts further commercially promoting of solid-state refrigeration. In this work, we adjusted the Co content to regulate the elastocaloric effect for the Ni_51.5Mn₂₅Ga₂₃Co_0.5. According to the results, the transformation strain and ratio of loading stress/transformation temperature (dσ/dT) were increased by replacing the Ni atoms with a little more Co, leading to an improvement of the stressinduced transformation entropy-change ΔS_σ. As a result, a huge ΔS_σ of 45.0 JKg^-1K^-1 is achieved in Ni₅₀Mn₂₅ Ga₂₃Co₁ alloy.

This study investigated the effect of pulsed electromagnetic field (PEMF) on proprioception through static balance after the short-term application of PEMF in people with functional flat feet. Forty-two volunteers participated in the study. The proprioceptive index of all subjects was measured before and after exposure to PEMF for 1 week. Seventeen subjects with normal feet were not exposed to a PEMF (Group I), and PEMF was applied to 17 subjects with normal feet (Group II) and eight with functional flat feet (Group III). In Group I, there were no significant differences in any of the variables. In Group II, a significant difference was observed only in the medio-lateral value when perturbation was applied in the antero-posterior direction. In Group III, significant differences in medio-lateral, antero-posterior, and vertical values were observed when perturbation was applied in the medio-lateral direction in Group III. Although there was a learning effect with repeated measurements, the improvement in balance after PEMF application indicates that PEMF has a positive effect on the nervous system in subjects with functional flat feet.

The solenoid coil is one of the most important design component for electromagnetic induction type coil gun system. When the voltage and current are applied across the coil, a uniform magnetic field is generated inside the coil and that is proportional to the number of coil windings, and the high-density magnetic field generated by the coil can be converted to mechanical energy by applying the strong electromagnetic force to a ferromagnetic material. At this time, the interaction between the current and magnetic field of the solenoid coil generates a strong electromagnetic expansive force between each coil wire. In this paper, we introduced a four-stage induction coil gun as the launcher system using high voltage pulsed power source. Also, we proposed both the method and formula to calculate the electromagnetic expansion force acting on the multi-winding layer solenoid coil gun by using energy transfer equations. When the current flows a solenoid coil, the expansion force is generated in the radial direction of the coil. The mathematical calculation results were verified by simulated ones.

Dipole magnet for a neutral beam injector is a magnetic device deflecting residual ions to an ion dump. For the high power neutral beam injection to fusion plasma, the heat load on the surface of the residual ion dump should be under acceptable level. We investigate the magnetic lens effect of the bending magnet for beam expansion cases. To intensify the magnetic lens effect, the height of the field clamp in the magnetic core is adjusted. The COMSOL Multiphysics software is employed to calculate a magnetic flux density for the dipole magnet, to trace an ion beam trajectory, and to evaluate a heat distribution on the beam dump. Simulation results reveal that the longitudinal magnetic field at the magnet entrance has a significant effect on the heat distribution in the ion dump surface, and hence the local heat flux is considerably alleviated by the field clamp with adjusting the height of the clamp.

This paper presents a design of magnetic resonant wireless power transfer (MR-WPT) system operating at 6.78 MHz with flexible resonator coils. The resonator coils are fabricated on an FR-4 substrate with a very thin thickness of 0.2 mm; therefore, they can be bent at various angles. With the bendable resonator coils, the configuration of the MR-WPT system will be more flexible, thereby increasing the applicability. However, the inductance, resistance, quality factor, and mutual inductance of the coils will be changed with the bending angle, thereby affecting the performance of the MR-WPT system. Detailed investigations of these changes were conducted by both simulation and experiment. Thus MR-WPT systems with flexible resonators can be designed for optimum performance. This proposed MR-WPT system can be applied in situations where system configuration requires high flexibility. Moreover, a bent resonator system can perform better than a flat resonator system in the inward bending configuration.