We report a systematic ¹H nuclear magnetic resonance (NMR) study in Mn₂(H₂O)[O₂C(CH₂)_nCO₂]₂ (MnDC-n, n = 3, 4, 6, 10), in which the separation between the Mn-O magnetic layers increases with increasing n. It turned out that the temperature dependence of the linewidth of the ¹H spectrum as well as of the spin-lattice relaxation rate 1/T₁ is well accounted for almost solely by the intralayer exchange couplings regardless of the value of n, implying that the magnetic properties of the MnDC-n system are essentially unchanged by varying the interlayer distance, and thus that the effective lattice dimension remains 2D even for the shortest interlayer distance, i.e., for n = 3. In contrast to the strong 2D nature in MnDC-n, however, a diverging behavior of 1/T₁ was observed at low temperatures in the extremely narrow temperature range for all n, verifying the occurrence of the long-range antiferromagnetic ordering at T_N = 5.3 K for n = 3 and T_N = 4.7 K for n = 4, 6, 10.

Quantum spin liquid (QSL) is an intriguing quantum phenomenon caused by quantum superposition and entanglement of spins and has attracted much attention because of the occurrence of unconventional ground states with high potential for applications in quantum computing. In particular, the realization of QSL in the thin film heterostructure provides a lot of possibility, however it has not been intensively studied due to the lack of measurement technique for magnetic properties of thin film heterostructure. In this paper, we discuss the possibility of observing the QSL states in the thin film heterostructure using torque magnetometry.

Recently, lanthanide and actinide compounds have been attracted lots of interest due to possible candidates of topological crystalline Kondo insulators, topological Weyl-Kondo semimetal, topological superconductors, and so on as well as topological Kondo insulators. In this paper, we review physical phenomena and topological properties in these strongly-correlated f-electron systems. We take some relevant f-electron systems as reference and briefly explain their electronic structures and topological properties.

Study on realization of Kitaev magnetism in two-dimensional honeycomb lattices is one of the cutting-edge research topics in condensed matter physics and quantum magnetism researches. In this paper I will briefly review recent theoretical and experimental ongoing progresses to engineer Kitaev magnetism in cobalt-based transition metal compounds.

Material design using machine learning is being used in various fields. In this study, along with the material properties calculated through the density functional theory (DFT), material’s features were obtained using only the chemical composition ratio using the python module of ‘Matminer’ and applied to machine learning. Based on the data of 164 magnetic materials from the Citrine database, the saturation magnetization value was predicted through three regression models of support-vector-machine, RandomForest, and XGBoost. Model optimization was performed through cross-validation and hyper-parameter tuning, and among the three models, XGBoost showed the best prediction performance. As for performance indicators, the R² score and root-mean-square-error, which are mainly used in regression analysis, were used to compare and analyze the performance of the model. Finally, predictions were made for Fe (iron) that was not in the database, and it was confirmed that the more characteristic factors in machine learning, the better the performance.

Methods for air busting munition (ABM) for bursting at a target distance have been developed because this method is very effective to precise attack when objects are blocked by wall and trench. Air busting munition technology also applied to eliminate the object in the air with high probability. Nowaday ABM is one of effective technology to defence from the drone attracts. In this study, we designed a multi-yoke system that can input muzzle velocity and air burst distance using serial data information. The serial data information used in this study are the same as typical serial communication; start bit, stop bit, data bit and parity bit which are corresponding to the magnetic field direction of the multi-yoke. Muzzle velocity is determined from the time of bullet passing from start bit yoke to stop bit yoke and the distance between these two yokes using MCU in the bullet. To determine fuse time of bullet is calculated from the fuse velocity and the target distance. To realize multi-yoke ABM method, FEM simulation was carried out. Dimension of yokes are focused on 25 mm bullet. Axial magnetic field component measurement at 1 mm distance from pole face of 6 mm U-sape yoke with 4 mm gap between yokes was possible to realize ABM with multi-yoke system.

We measured the permeability of CoFeB thin films by using the second harmonic signals of planner Hall resistance (PHR) sensor in the low frequency range of 10 Hz~50 kHz. The low frequency permeability of CoFeB thin film was compared with the microwave permeability measured by using one-turn coil as well as the real permeability calculated by LLG equation. We confirmed that the low frequency permeability of CoFeB thin film was correspond to the initial permeability of CoFeB thin film. Thus the second harmonic signals of the PHR sensor can be applied to the low frequency permeameter with compact, high resolution and low power consumption.

A clip-type pulsimeter equipped with a semiconductor Hall device was developed by attaching a small permanent magnet to the center of the radial artery near the wrist to measure the change in the magnetic field generated by the movement of the pulse. Characteristics of the spatial pulse wave velocity (SPWV) measured continuously for 1 hr during which a magnetic sensing Hall element pulsimeter and a photoplethysmography device were worn at the same time with spinal stimulation and thermal treatment by a personal stimulator were investigated. Hypertensive male and normal female in their 20 years old were used as test subjects, and the SPWV data obtained during spinal stimulation and thermal therapy were graphed and then linear regression analysis was performed. The two subjects with hypertension and normal blood pressure showed a tendency to improve the peripheral vascular characteristics differently, with the SPWV gradually decreasing and increasing from 0.64 m/s and 3.84 m/s to 0.83 m/s and 2.69 m/s, respectively. Based on the results of this study, it is expected that vascular characteristics data for individual healthcare will be accumulated as big data and utilized to develop digital healthcare artificial intelligence algorithms for vascular diagnosis.

SRMs use usually three or more phase motors, but single-phase or two-phase SRMs are used to achieve price competitiveness in the small and medium-sized servo motor field. However, if (number of stator poles/number of rotor poles) of SRM= integer, these SRMs have not the capability of self-starting with a basic magnetic structure. it solves the actuating problem by additionally using a permanent magnet or by changing the size of the air gap of the rotating pole. This paper presented the analysis of the magnetic structure and design considerations of the 8/4 TPSRM with self-starting, which has four rotor poles that consist of different rotor pole arc pairs with a constant air gap, and used the magnetic structure analysis program using the finite element method (FEM) to prove its validity.

The electromagnetic (EM) wave absorption characteristics of multi-stacked magnetic ceramic absorber-epoxy composites were studied. First, the M-type hexaferrite SrFe_12-2xCo_xTi_xO₁₉ (x = 1.1, 1.2, 1.3) powders having differrent maximum absorption frequencies were synthesized, and 10 wt% epoxy was mixed and pressed to prepare toroidal-shaped composites. The reflection loss (RL) spectra were obtained by direct S11 measurement and calculation from the permittivities (ε', ε'') and permeabilities (μ', μ'') spectra. The maximum absorption performances, that is, the minimum RL value, satisfies RL < -30 dB for all the 3 samples and the frequencies at minimum RL points (f_RLmin) of the x = 1.1, 1.2, and 1.3 composites were 13.5, 9.7, and 6.5 GHz, respectively. Three samples were stacked in various stacking orders of ABC, ACB, BAC, BCA, CAB, and CBA to obtain RL spectra according to the stacking sequence. The RL spectra according to the stacked order were not significantly different from each other. The measured RL spectra of these stacked samples were well fitted with the RL spectra calculated using the volume averaged ε', ε'', μ', μ'' values of the A, B, and C samples. Next, RL spectra were measured with changing the stacking order of La_0.7Sr_0.3MnO₃ (LSMO) powder-epoxy (10 wt%) sample and SrFe_12-2xCo_xTi_xO₁₉ (x = 1.25). Because LSMO is conductive, the LSMO-epoxy composite has much higher ε', ε'' in the entire measurement frequency band than the insulating hexaferrite composites. The RL spectrum showed a large difference according to the stacking order of the two layers. When hexaferrite is positioned on the side where EM wave was irradiated, much better EM absorption characteristics could be obtained in a wide band, because LSMO layer highly reflects EM wave in a wide frequency range due to its large ε', ε''.

The warship without degaussing coils was demagnetized by applying Flash-D to prevent damage from magnetic mines installed on the sea. Since the degaussing equipment is not installed, the induced magnetization (IM) by the earth’s magnetic field can’t be removed, so the Flash-D protocol removes the PLM (Permanent Longitudinal Magnetization) and intentionally magnetizes PVM (Permanent Vertical Magnetization) to compensate IVM (Induced Vertical Magnetization) at the same time. However, researches on determining the magnetic field to magnetize the target PVM is insufficient, and it takes a lot of time because small magnetic fields are continuously applied in addition to the Flash-D protocol until the target PVM is magnetized. Therefore, in this paper, the method for determining the vertical magnetic field was analyzed and verified by experiments.