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We investigated the magnetoconductivity Δσ(H)≡1/ρ(H)-1/ρ(0) in a wide range of magnetic fields for three-dimensional indium oxide films doped with zinc, tin, or gallium in the range of resistivity ρ(300K) between 4.1×10-6 Ωm and 1.7×10-3 Ωm. The weak localization theory was fitted to data for Δσ(H) at various temperatures in the range 2.0 K≤T≤50 K by the use of suitable characteristics Dτin(T) and Dτso, where D, τin, and τso are the electron diffusion constant, inelastic scattering time, and spin-orbit (s-o) scattering time, respectively. It was found that (i) for films with a large value of ρ, the sign of Δσ(H) changes from positive to negative with decreasing temperature as a precursor to an anti-weak localization effect; (ii) the ratio τso/τin decreases from ≈4000 to≈4.0 with increasing ρ; (iii) the strong ρ dependence of Dτso cannot be explained by the model with a constant atomic number Z in a formula τso∝1/Z4 proposed by Abrikozov and Gorkov Zh. Eksp. Teor. Fiz. 42, 1088 (1962); [Sov. Phys. JETP 15, 752 (1962)]. As a reason for this ρ dependence, we suggest that the s-o scattering changes with increasing ρ from light oxygen atoms to heavy atoms, i.e., indium, zinc, and gallium, because of the decrease in the number of oxygen vacancies acting as s-o scattering centers. [ABSTRACT FROM AUTHOR]

Magnetic flux concentration is a very important technique for the effective generation of high magnetic fields. We propose the use of the diamagnetism of a high Tc bulk superconductor (HTS bulk) instead of ferromagnetic materials such as Ho and Dy. We fabricated a magnetic field concentrator using Gd-Ba-Cu-O bulk. The essential point was slits to suppress the current along the circumference. The concentrator was cooled at the center of a superconducting magnet with liquid helium. By increasing the external field to 1.00 T, a magnetic flux density of 3.20 T was obtained at the center of the concentrator. At an external field of 2.00 T, a field of 5.65 T was also obtained. A magnetic lens using HTS bulk was successfully demonstrated. The experimental results were well explained by numerical analyses assuming HTS bulk as a perfect conductor. [ABSTRACT FROM AUTHOR]

We have developed a high-strength Ta-reinforced Nb3Sn conductor for high-magnetic-field magnets. In our previous work, it was demonstrated that the Ta-reinforced Nb3Sn conductor had good characteristics against mechanical stress and strain. In this study, we made a 2-D calculation code for a stress-strain analysis, and derived the stress and strain of the magnet using some physical values such as the Young's modulus of the conductors, magnet dimensions and so on. According to the calculation results of some model magnets, the Ta-reinforced Nb3Sn conductor could be used without extra support structures. Hence, the conductors are fit for high-magnetic-field and large-scale magnets such as NMR and SMES magnets. [ABSTRACT FROM AUTHOR]

The Tsukuba Magnet Laboratory (TML) and the High Field Laboratory for Superconducting Materials collaborated on the design study of a 50 T-class hybrid magnet. The highest fields of the hybrid magnet were examined with the existing 15 MW DC source at the TML used for the resistive insert magnet. The strength of the Cu-Ag wire exceeds 1400 MPa in ultimate tensile strength (UTS). Several upper-design stresses corresponding to the Cu-Ag wire strength were placed on Bitter disks to evaluate the resistive insert. The design was conducted with two inner radii, 29 mm and 19 mm. Resistive insert magnets are consist of three-layered coaxial Bitter coils operated with the 20 T outer superconducting magnet with a room temperature bore of ~400 mm. In this hybrid magnet, a UTS of 1200 MPa is needed for the Bitter disks of the resistive insert to generate 46 T. [ABSTRACT FROM AUTHOR]

The Tsukuba Magnet Laboratory (TML) of the National Institute for Materials Science has been producing epoch-making achievements in the history of high-field magnets. TML is also known as one of the largest high magnetic field facilities in the world and opened to domestic and international users. As a milestone in the 1-GHz NMR project, a 920-MHz high-resolution NMR magnet using Nb3Sn innermost coil was developed in order to accelerate studies to obtain stereoscopic protein structures. Measurements for analyzing the stereoscopic structure of protein molecules using 920 MHz NMR magnet have been performed since July 2002. [Copyright &y& Elsevier]

We report the magnetization process on the S=1/2 antiferromagnetic Heisenberg chain [PM·Cu(NO3)2·(H2O)2]n (PM=pyrimidine). It has become clear that the staggered magnetic field plays an important role in the magnetic behavior from magnetic susceptibility and specific heat studies on single-crystalline samples. The magnetization curve for a single crystal of [PM·Cu(NO3)2·(H2O)2]n does not show a divergent slope, but rounding behavior at the saturation field due to the effect of the staggered magnetic field even at 100 mK. [Copyright &y& Elsevier]