Mn_2/3−xZn_1/3+xFe₂O₄ (x = 0, 0.1, 0.2, 0.3) spinel ferrites samples were prepared by conventional ceramic process and the effects of the composition, sintering temperature and atmosphere (air, nitrogen) on the structure and magnetic properties were investigated. X-ray diffraction (XRD) analysis revealed that all the samples sintered at T ≥ 1200 ℃ have single spinel phases. The average grain size of the samples increased with increasing sintering temperature, although a clear dependence of the microstructure on x were not shown. Magnetization curves measured on the wire-wound toroidal samples by using a B-H curve tracer showed soft magnetic behaviors for all the samples. The magnetic flux density value and complex permeability (μ = μ' + jμ'') spectra sensitively varied with x and processing conditions. The highest dc permeability of dB/dH = 8896 could be achieved at the x = 0.1 sample sintered in nitrogen at 1250 ℃.

The nucleation and growth processes of iron oxide nanoparticles were analyzed by ferromagnetic resonance (FMR) technique. The FMR signals were measured for aliquots samples sequentially taken from the reaction solution during thermal decomposition process. The Fe(OL)₃ precursors produce the Fe-OL monomers at 200 ℃, which is contributed to the nucleation of iron oxide nanoparticles. In initial growth stage, the iron oxide nanoparticles have γ-Fe₂O₃ structure with positive anisotropy constant. As temperature increases over 260 ℃, the antiferromagnetic FeO layer is formed on the surface of γ-Fe₂O₃ nanoparticles by Fe-OL monomer reduction. These nanoparticles are transformed from γ-Fe₂O₃ to Fe₃O₄ structure with negative anisotropy constant during constant temperature stage of 300 ℃.

We investigated the magnetic anisotropy energy of 2-dimensional transition-metal (TM= Fe,Co,Ni) oxide molecular magnet using 1^st principle density functional method with spin-orbit interaction. The calculation results show that the magnetic easy-axis is along the line between TM and TM atoms and the hard-axis is perpendicular to the TMO plane except NiO. Partial electron occupation of d_yz orbital induce the unquenched orbital momentum and LS coupling. It makes the easy-axis and hard-axis along x and z direction, respectively. For TMO, FeCoO₂ represents the largest anisotropy energy because of nearly half filled d_yz orbital.

The systolic blood pressure and systolic time were measured and analyzed by using the oriental-western fusion patient monitor and the clip-typr pulsimeter equipped with permanent magnet and Hall device. The systolic blood pressure and systolic time were measured before and after the treatment of a personal combination stimulator capable of thermal therapy and massage. The average and standard deviation of the difference between before and after treatment for the 20-year-old male and female subjects were measured and analyzed. As a result, the systolic blood pressure decreased by 4.27 mmHg~5.36 mmHg with significance probability p = 0.01, and the systolic time increased by 1.27 ms~2.03 ms with significance probability p = 0.05 after thermal and massage treatment. On the other hand, the changes in body temperature and oxygen saturation were minimal, and diastolic blood pressure and pulse rate were slightly lower. It is expected that the result of various biometric information obtained by using the personal combination stimulator as therapy medical apparatus, the oriental-western fusion patient monitor and the clip-type pulsimeter as diagnosis medical apparatus, will provide the important medical information in the age of aging.

In recent, PNI sensor corporation has been released geomagnetic field sensor with high performance. This sensor uses a new principle measuring the period of digital output pulse of L/R oscillator circuit which is connected to the solenoid coil inductor wound on high permeability amorphous wire. In this paper, we design L/R oscillator circuit based on the PNI’s principle and connect the circuit to the solenoid coil inductor containing Cu core/Ni₈₀Fe₂₀ shell composite wire fabricated by electrodeposition. We investigate applicability of this system to geomagnetic field sensor.