Mn-substituted Li-Zn-Cu ferrite polycrystal is known to be a high-frequency ferrite. The authors recently clarified that this ferrite exhibits strong temperature-dependent magnetic properties. To our knowledge, detailed information on the temperature dependence of this new temperature-sensitive ferrite has not been reported. In the present study, several polycrystalline ferrites were fabricated while controlling the Li-ferrite content to investigate the chemical composition dependence of the temperature characteristics of their magnetic properties. As a result, it was clarified that the strong temperature sensitivity of the Li-Zn-Cu ferrite depended on the large temperature coefficient of the anisotropy constant of Li-ferrite. In addition, the smaller Li-ferrite content intensified the temperature dependence of the apparent anisotropy field, hence reinforcing the temperature-dependent magnetic properties.

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The structure and magnetic properties of LiMn_2-XMg_XO₄ (X < 0.5) compounds prepared by the sol-gel technique were studied by means of powder X-ray diffraction and magnetic measurement. Specimens with X < 0.2 had a cubic symmetry of Fd3m, while those with X > 0.3 exhibited extra reflections attributable to the P4₃32 space group, where Mg²⁺ and Mn⁴⁺ have 1:3 cation ordering on a 16d octahedral sublattice. Mg²⁺-substitution led to the enhancement of low-temperature magnetic susceptibility, indicating magnetic phase conversion from antiferromagnetic to ferromagnetic characters. This was attributed to variation of the average Mn valence state. The Mn valence state was sensitive not only to the substitution but also the preparation conditions. Ideally, ferromagnetic ordering was expected in specimens of the compound with X = 0.5. However, both the magnetization and the Curie temperature depended on the preparation temperature (T_prep): they took maximum values (M_s = 4.68μ_B, T_c = 23K) at T_prep = 700°C, where the chemical composition of the specimen was the closest to the stoichiometric composition. The magnetic properties of Li-Mn-Mg spinel oxides were briefly discussed in comparison with those of Li-Mn-Ni spinel oxides.

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The exchange bias field and its training effect, the MR ratio as a function of the measured angles, and the interlayer coupling of Fe_0.7Co_0.3/Cr-nano-oxide-layer (NOL) spin-valves (SVs) were studied to investigate the magnetism and the structure of Fe_0.7Co_0.3/Cr-NOL. Strong negative interlayer coupling was observed, which suggests Fe_0.7Co_0.3/Cr-NOLs have very flat surfaces. However, the unusual tendency of the dependence on temperature of the exchange bias field and its training effect were observed due to the twisted coupling through on Fe_0.7Co_0.3/Cr-NOL. As a result, this suggested that Fe_0.7Co_0.3/Cr-NOLs include several different magnetic components, such as ferrimagnetic components of Co²⁺Fe³⁺_2-tCr³⁺_tO₄ and Fe²⁺Fe³⁺_2-tCr³⁺_tO₄ and antiferromagnetic components of Cr₂O₃-Fe₂O₃ and CoO.

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We investigated the influence of a direct current on domain wall magnetoresistance (DWMR) elements with Fe_0.5Co_0.5-AlO_x nano-oxide-layer including ferromagnetic metal nanocontacts. The current induced microwave oscillation and changes in the shape of R-H curves with increase of sense current were observed. The origin of these results are considered to be spin transfer effect on the confined domain wall in ferromagnetic metal nanocontacts and current induced magnetic field adjacent to ferromagnetic metal nanocontacts because of high current density. Furthermore, our study indicates a high likelihood of correlation between microwave oscillation and R-H curves in high sense current. We infer current induce microwave oscillation in the higher resistance state which was observed after the jump of resistance by high sense current. Moreover, it is suggested that there is some correlation between oscillation frequency and degree of twist of magnetization in a domain wall.

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Thin films of ordered double perovskite Sr₂CrReO₆ were sputter-deposited on SrTiO₃ (001), (111), LaAlO₃ (001) substrates. With high quality thin films of the double perovskite Sr₂CrReO₆, we have investigated the electronic state of the inside of the Sr₂CrReO₆ thin films by Synchrotron Radiation photoelectron spectroscopy (XPS). The Re 4f spectrum of Sr₂CrReO₆ has shown a multiple peak structure, which originates from the electronic state of Re in half-metallic Sr₂CrReO₆. Moreover, it has been found that the electronic densities of states clearly exist on the Fermi energy.

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We designed a flexible pickup coil for torque sensors in which the offset is reduced as a result of the asymmetric structure, which was created in order to obtain an easy connection. The mutual inductance was calculated for all the possible coil patterns of an asymmetric configuration, and the coil pattern that exhibited the lowest mutual inductance was selected the best design for the pickup coil. In addition, the performance of a flexible pickup coil incorporating this design was evaluated by observing its offset voltage, response to the uniaxial magnetic anisotropy, and input-output characteristic. The results showed that the offset voltage was lowest in an asymmetric coil pair. The response to the uniaxial magnetic anisotropy showed an output pattern as the axis torque sensor. The input and output characteristics almost accorded with those of a conventional symmetric model coil pair.

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We measured somatosensory evoked fields (SEFs) by giving electric stimulus to the fourth finger of the right hand (five normal subjects) with a 39-channel SQUID system, which can measure magnetic-field components perpendicular (Br) and tangential to the scalp (Bθ, Bφ) simultaneously. Singular value decomposition (SVD) was applied to the measured SEF data for preprocessing (noise reduction). To investigate the relationship between phase lag and stimulus repetition frequency (SRF), the delay time of a component synchronized with the SRFs was calculated by convoluting the reference signal and the measured SEF. The inter-stimulus interval (ISI) for the SRFs were ten patterns from 3.00 to 27.03 Hz including two to six trains of stimulation-data length for analysis and also a recovery period of 500 ms after the final train. A dominant slope appeared for two ranges (below 8 Hz, and 8 to 20 Hz) in all magnetic components. No marked slope was obtained at an SRF of more than 20 Hz to the transient SEF waveforms. We tested the significance of the linear regression slope (β≠0, and P<0.05). Finally, we did a simulation based on the results of the phase lag characteristics.

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