Showing papers by "Seong-Cho Yu published in 1991"
TL;DR: In this paper, the X-ray diffraction pattern, the electrical resistivity, and the magnetization M (T,H ) of the Bi 1.6 Pb 0.4 Ca 2 Sr 2 Cu 3 Oy superconductor with Tc =107 K were measured.
Abstract: We present measurements of the X-ray diffraction pattern, the electrical resistivity, and the magnetization M ( T,H ) of the Bi 1.6 Pb 0.4 Ca 2 Sr 2 Cu 3 Oy superconductor with Tc =107 K. The upper critical field Hc 2 is obtained from magnetization measurements. The magnetization M ( T ) is linearly increased with temperature in a range of about 15 K below Tc . From the slope ∈ Hc 2 /∈ T near Tc , the zero-temperature upper critical field Hc 2 (0) of 84 T is estimated. Also, the lower critical field Hc 1 (0) is obtained 112 Oe from the deviation of the magnetization curve. We estimate the fundamental superconducting parameters: the coherence length ξ 0 =20 A, the penetration depth λ 0 =2700 A, the Ginzburg-Landau parameter κ=136, and the jump in the specific heat Δ C / Tc ≅2.7 mJ/mol K 2 .
4 citations
25 Mar 1991-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: The atomic structure of single roll-quenched amorphous Fe80−xCoxSi6B14 (0 ≤x≤80 at.%) alloys have been studied by X-ray diffraction as discussed by the authors.
Abstract: The atomic structure of single roll-quenched amorphous Fe80−xCoxSi6B14 (0 ≤x≤80 at.%) alloys have been studied by X-ray diffraction. The interference functions, atomic distribution functions, and radial distribution functions were calculated from the X-ray diffraction intensity data. The nearest-neighbor distance decreases from 2.560 ± 0.008 A to x = 0 (Fe80Si6B14) to 2.505 ± 0.008 A for x = 80 (Co80Si6B14), while the average coordination number of 12.50 ± 0.15 is independent of x. These results are consistant with the measured densities of the samples, which are found to increase with increasing cobalt content.
3 citations
TL;DR: The angular dependence of the magnetization of Bi1.7Pb0.3Sr2Ca2Cu3Oy was studied by rotating the sample relative to the applied magnetic field.
Abstract: The angular dependence of the magnetization of Bi1.7Pb0.3Sr2Ca2Cu3Oy was studied by rotating the sample relative to the applied magnetic field. At low fields and at the nitrogen temperature, the irreversible part of the field-cooled magnetization, Mirr, rotates with the sample like a rigid body. Above some angle *, the rigid nature of the sample is diminished, and a part of Mirr disappears. This feature is quite similar to what had been observed in Y1Ba2Cu3O7 compounds.
2 citations
15 Mar 1991-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: Amorphous (Fe1−xNix)75Si10B15 (0.1) alloys were prepared by the rapid quenching technique and their magnetization measurements have been performed by utilizing a vibrating sample magnetometer from 77 K up to 800 K.
Abstract: Amorphous (Fe1−xNix)75Si10B15 (0.1 ⩽ x ⩽ 1, the step of x is 0.1) alloys were preparedby the rapid quenching technique and their magnetization measurements have been performed by utilizing a vibrating sample magnetometer from 77 K up to 800 K. The Curie temperature, Bloch coefficient, and range of exchange interaction were calculated from the temperature-dependent saturation magnetization curves. The low temperature dependence of magnetization is in good agreement with Bloch's relation, M s (T) = M s (0) (1 - BT 3 2 - CT 5 2 ) . The range of exchange interaction becomes shorter with the addition of nickel concentration. The observed mean square ranges of exchange interaction shows that this alloy system loses the ferromagnetic ordering when x is larger than 0.9.
TL;DR: TbGdFeCo and TbFeCo thin films were prepared by dc magnetron sputtering and the magnetic anisotropy constants were calculated by using Miyajima method as mentioned in this paper.
Abstract: TbGdFeCo and TbFeCo thin films were prepared by dc magnetron sputtering. Deposition conditions were background pressure of below 2 × 10-6 Torr and Ar pressure of about 5∼20 mTorr. The bias voltage was about -150∼0 volt. Torque and hysteresis loop of the samples were measured by torque magnetometer and VSM with an applied field of 7.4 kOe and 10 kOe, respectively. The magnetic anisotropy constants were calculated by using Miyajima method. The single layer thin films with a thickness of about 2000 A were prepared with replacing Gd with Tb. Here, it could be known Ku decreased with increasing Gd instead of Tb and took a sudden turn for the decrease when bias voltage was zero. All of the single layer thin films showed in-plane anisotropy. In case of multilayer thin films, the samples were prepared with varying thickness, and the composition of the samples were Tb24(Fe-Co)76. Most multilayer thin films represented perpendicular anisotropy.