M. Sato

Oblique incidence effects in evaporated iron thin films

Abstract Magnetic properties, electrical resistance and microstructures of evaporated iron thin films deposited at an oblique angle of incidence have been investigated. The structure differs along the thickness direction and contains interstices. It is observed by the dark field image that the columns formed appear to be single-crystals at high incidence angles.

Pressure-induced phase transition in Fe-Se and Fe-S systems with a NiAs-type structure

Abstract High-pressure X-ray diffraction measurements have been made on Fe-Se and Fe-S systems with a NiAs-type structure up to 10 GPa. Phase transitions take place at p c =4.1−8.5 GPa. The compressibility of c (κ c ) changes at p c and κ c in the high-pressure phase is nearly equal to that of CoSe or CoS. The correlation between the magnetism and the lattice spacing c in these compounds is discussed on the basis of the presents.

Magnetoresistance in Ni-Fe/Cu multilayers formed by sputtering

Abstract The dependence of magnetoresistance on the thickness of Cu layer, the thickness of magnetic layer, the thickness of buffer layer, the number of layered stack and the composition of magnetic layer has been investigated for the Ni x Fe 100- x /Cu multilayers.

Magnetoresistance in Ni-Fe/Cu Multilayers

Ni<inf>80</inf>Fe<inf>20</inf>/Cu multilayer films were prepared on glass substrate by magnetron sputtering. The dependence of the magnetoresistance on the thickness of the Cu layer, the thickness of the Ni-Fe layer, the thickness of the buffer layers for Fe, Ni<inf>80</inf>Fe<inf>20</inf> and Cu, and the number of bilayers, was investigated. The MR ratio peaked at d<inf>Cu</inf>= 10Å, where the MR ratio was about 20% at room temperature. When the thickness of the Ni<inf>80</inf>Fe<inf>20</inf> layer was varied, the MR ratio had a broad peak from d<inf>Ni-Fe</inf>=15 to 30Å. The interlayer exchange interaction was evaluated as 3×10^¿2 erg/cm², irrespective of the thickness of the buffer layer. The MR ratio increased with the number of bilayers N, and reached saturation when the total film thickness was about 800 to 1000Å.

Magnetic properties of Mn1−xTixSb and Cr1−xCoxSb (O⩽x⩽1)

Abstract Magnetic measurements have been carried out on Mn 1− x Ti x Sb and Cr 1− x Co x Sb. The behavior near the magnetic critical concentration brings out the contrast between two systems. A spin glass phase is found in Mn 1− x Ti x Sb with 0.70≲ x ≲0.90. The Neel temperature of Cr 1− x Co x Sb falls drastically with increasing x and around x =0.5 and approaches 0 K at x =0.55. The behavior of the latter system is attributed to the concentration-dependent magnetic moment of Cr atoms.

Magnetic properties of iron thin films evaporated at oblique incidence

Abstract Evaporated iron thin films of thickness in the range 200 to 8500 A were deposited on plastic substrates at oblique incidence angles ϕ. The magnetic properties of films prepared at ϕ = °0 to °80 were investigated. The easy axes of the films at ϕ = °75 and °80 are parallel to the incidence plane, whereas it is perpendicular for an incidence angle less than °65. An abnormal field dependence of the magnetic torque in the film plane of the sample at ϕ = °80 was observed. The magnetic torque decreased with increasing external field beyond a certain value. This abnormality is explained by assuming that the magnetization, which lies along the easy axis of the columns, cants under the presence of the external field. Measurements for films evaporated on plastic and glass substrates, indicated that the fine-structured layer near the substrate also influences the magnetic properties.

Magnetic phase diagram of (Fe,Co)7S8 and (Mn,Ti)Sb

Magnetic, X-ray and NMR measurements have been made on (Fe,Co)7S8 and (Mn,Ti)Sb. Around the magnetic critical concentration, the simple disappearance of ferrimagnetism in the former makes a marked contrast with spin glass-like behavior in the latter. These results are discussed with a correlation between magnetism and lattice spacing c in NiAs-type compounds.

FMR Study of Ni-Fe/Cu Multilayer Films

The interlayer exchange coupling strength of 80Ni-Fe/Cu multilayer films prepared on a glass substrate by magnetron sputtering was studied by ferromagnetic resonance. The exchange coupling strength was evaluated by assuming a weak perpendicular magnetic anisotropy and fitting the data of the resonance fields and peak intensities. It exhibited a broad peak when the Cu thickness was 10.8Å, and increased linearly in proportion to the number of bilayers.

Magnetic integrated passives for information and communication technology

Mobile communication traffic is continuously doubling in recent years.

A Simple Method to Reduce Torque Ripple of SR Motors using Freewheeling mode for Electric Vehicles

This paper proposes using freewheeling mode as the method of torque ripple reduction. It is confirmed from the simulation that the torque ripple has been decreased by the method. Torque ripple reduction by freewheeling mode is especially effective at low-speed and large torque area. So, the proposed method is suitable for low cost drive of electric vehicles.