The algorithm for computation of parameters of soft ferrite to simulate it with the Jiles and Atherton model is presented. The algorithm tries to reconstruct initial magnetization curve of the ferrite using very few data taken from catalogue of ferrites. The algorithm is illustrated by parameters extraction for a commercially available ferrites.

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The demand for buildings constructed from non-magnetic materials has greatly increased, for facilities in which precise measurements, such as nuclear magnetic resonance (NMR) spectroscopy or investigations into the biological effects of magnetism, are carried out. In this paper, the magnetic characteristics of architectural materials for non-magnetic buildings are investigated. We found that non-magnetic bars, cement, and sand have lower magnetization than the SUS304 plate commonly, which is used as the reference for a low-magnetic material in architecture, but ferromagnetic carbon steel bars show very high magnetization. The magnetization of a plastically deformed portion of SUS304 is about twenty times higher than that of an undeformed one. We also discuss demagnetization by heat treatment for deformed samples, especially the characteristics of the magnetization's dependence on temperature for heat-treated SUS304. The elimination of plastically deformed portions of architectural materials and suitable heat treatment for deformed materials is of great importance in the realization of non-magnetic buildings.

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We investigated the relationships between the head field strength and the time response of a single-pole-type head and the thickness of its soft under layer, using a micromagnetic simulator that takes into account the full interactions between SPT head and a double-layered medium. The results obtained showed that the head field strength is dramatically enhanced by a very thin soft under layer of 20 nm and that it saturates with a relatively thin layer of 60 nm. Moreover, the delay time and the response of the head field to the exciting field increase with a thicker soft under layer.

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We investigated electrical transport properties in the current-perpendicular-to-plane (CPP) configuration for micro-fabricated manganese oxides (La_1-xSr_xMnO₃). The resistivities in the CPP configuration for La_0.9Sr_0.1MnO₃ and for La_0.7Sr_0.3MnO₃/La_0.9Sr_0.1MnO₃ decreased with an increase in the measuring current while the ferromagnetic Curie temperatures for the same materials increased. We found no qualitative difference between La_0.9Sr_0.1MnO₃ and La_0.7Sr_0.3MnO₃/La_0.9Sr_0.1MnO₃, indicating that spin-polarized currents from La_0.7Sr_0.3MnO₃ into La_0.9Sr_0.1MnO₃ had no major effect on the transport in La_0.9Sr_0.1MnO₃.

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We report on the magnetic properties of highly homogeneous Fe₁₆N₂ nanoparticles prepared by an ammonia nitrification method. Mössbauer spectroscopy experiments revealed the large hyperfine field characteristic of Fe₁₆N₂. TEM observation showed that the particles are covered with oxide shells. The saturation magnetization and the coercive force are 108 emu/g and 3450 Oe, respectively. The angle dependence of the MH curves for the magnetically aligned samples indicates that the magnetic interaction between the particles is negligibly small, suggesting that the magnetocrystalline anisotropy is significantly large. Under the assumption that only the ferromagnetic core is responsible for magnetization, the magnetization and the anisotropy constant of the core Fe₁₆N₂ powders were estimated as 196±10 emu/g of Fe and K ^fp_U1 =4.1 ± 0.4 x 10⁶ erg/cm³, respectively.

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Fe/Ni-Zn-Cu ferrite composites films were prepared by the aerosol deposition (AD) method using double nozzles to control the Fe content in AD composite films. As aerosol flow of fine particles is produced by the vibration of aerosol chamber and carrier gas, the vibration frequency of the Fe chamber, which is one of AD conditions was considered to be one of the most effective parameter for controlling Fe content in AD films. When the vibration frequency was increased from 300 rpm to 330 rpm, the thickness and saturation magnetization of the films increased linearly, and the μ_r” value of the films also rose to a maximum of 18 (330 rpm). SEM-EDX analysis showed that AD composite films prepared at vibration frequencies of 300 rpm, 310 rpm and 330 rpm contained 20% 65% and 92% Fe, respectively, and revealed clearly the linear change in the Fe composition with the vibration frequency. In addition, the sample prepared at vibration frequency of 330 rpm showed the maximum noise suppression effect (Δ P_loss/P_in) of 0.59, which was comparable to the value in our previous work ¹⁾. This re sult demonstrates that the Fe composition in AD composite films can be controlled by using double nozzles.

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Implant medical devices are physically isolated from power sources required to supply driving energy to them. A well-known contactless power transmission technology is the transcutaneous energy transmission system (TETS), which applies electromagnetic induction between two disk-like spiral coils (a primary coil outside the body, and a secondary coil inside the body). Implant devices that require a temperature rise for their actuation must be prevented from overheating, and transcutaneous control and monitoring of the devices? temperature is necessary. A small inductor with a thermosensitive ferrite core was developed as a thermo-sensing device. This inductor controls the temperature automatically inside the body in combination with TETS. A coupling factor change between the two coils of a TETS transformer also affects the stability of power transmission characteristics. A suitable excitation frequency was designed to ensure stable driving. The control system referred to above has been applied in an artificial anal sphincter system that is now being developed, and appropriate driving has been observed.

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