A. Yamagishi

High magnetic field facility at Osaka University

Abstract The high magnetic field facility of Osaka University, equipped with several kinds of non-destructive magnets, is described. The field strength produced for practical use is up to 80 T and time durations are from 0.4 ms to 40 ms. Various kinds of experiments, from physics to biology, are carried on there.

Diamagnetic Orientation of Polymerized Molecules under High Magnetic Field

Diamagnetic alignment of polymerized organic molecules is discussed both from the theoretical and experimental points of view. When a number of molecules aggregate with their diamagnetic principal axes along the same direction, the resultant diamagnetic anisotropy energy becomes comparable to the thermal energy and the aggregated molecule can align under a conventional magnetic field, even at room temperatures. Polymerization of fibrin molecules is observed under magnetic fields up to 8 Tesla and considerable alignment is found. Partial alignment is seen even at 1 Tesla which means that blood clotting is influenced by use of the conventional superconducting magnet.

Effects of static magnetic fields of erythrocyte rheology

Abstract The orientation of normal erythrocytes in a uniform static magnetic field (8 T maximum) has been investigated microscopically and photometrically. 1. (1) The intact erythrocytes were oriented with their disk planes parallel to the magnetic field because of the diamagnetism of the cell membrane components, particularly the transmembrane proteins (e.g., Band III, glycopholin) and the lipid bilayer. 2. (2) In contrast, the glutaraldehyde-fixed erythrocytes were oriented perpendicular to the field, perhaps because of the paramagnetism of the membrane-bound methemoglobin. 3. (3) The orientation was established within 5 s in a dilute suspension (5 × 103cells μl−1) as estimated from the change in light scattering after exposure to the magnetic field.

Magnetic field effect on the polymerization of fibrin fibers

Abstract The alignment of organic molecules polymerized in magnetic fields is investigated theoretically and experimentally. Aggregation of a number of molecules with their axes along the same direction makes it possible to orient them along the applied magnetic field even at room temperature. Polymerization of fibrin fibers with considerable alignment is observed in magnetic fields up to 8 T. Partial alignment is seen even at 1 T.

Upper critical field and resistivity of single-crystal EuBa2Cu

A wide-temperature-range profile of the H/sub c//sub 2/-T curve for the superconducting 1:2:3 compound is presented. The data were obtained from a EuBa/sub 2/Cu/sub 3/O/sub y/ single crystal under a pulsed magnetic field up to 50 T along the c axis. H/sub c//sub 2/ at 4.2 K is 27.5 +- 2.5 T for the onset of the resistivity. The residual resistivity is roughly estimated to be about 50 ..mu cap omega.. cm. The magnetoresistance is positive and the general features of the superconducting properties except T/sub c/ are well sketched by the Bardeen-Cooper-Schrieffer dirty-limit model. The anisotropies in H/sub c//sub 2/ and the resistivity are also discussed

Specific-Heat and Magnetic-Behavior of UTGe Compounds

The temperature dependence of the magnetic susceptibility, electrical resistivity, and specific heat, as well as the magnetization in fields up to 35 T, of polycrystalline samples of UTGe (T=transition metal) compounds has been studied. The development from nonmagnetic UCoGe and URuGe through the weak ferromagnet URhGe, which displays the highest γ value, to complicated types of the local 5f‐moment ordering for T=Pd, Ni, and Pt is in agreement with the expected trends of gradually reduced 5f‐d hybridization.

Interplay of antiferromagnetic and antiferroquadrupolar interactions in DyAg and other rare earth intermetallic compounds

Abstract The study of the magnetoelasticity of the cubic (CsCl-type) rare earth intermetallic DyAg allows us to determine the strength of both the magnetoelastic coupling and the quadrupolar pair interactions. These latter ones are observed to be negative (antiferroquadrupolar type) for the tetragonal symmetry as well as for the trigonal one. They drive the magnetic structure to be triple- q at low temperature: the cubic magnetic cell consists of four pairs of ferromagnetic moments pointing along each of the treefold axes. At high temperature, it is replaced by a double- q structure, then, immediately below T N , by a modulated arrangement. The magnetization processes have been thoroughly studied along the three main axes in fields up to 40 T and compared with previous results in isomorphous DyCu and in the AuCu 3 -type compound TmGa 3 . The sequences under field of the different magnetic structures are identical and mainly determined by the crytalline electric field and the antiferroquadrupolar interactions. These 3 compounds do not set a peculiar case, but seem to belong to a larger family of cubic compounds with multiaxial structures governed by antiferroquadrupolar terms.

Multistep magnetization of single crystal TbNiSn and DyNiSn in high fields

Abstract Magnetic and transport properties are reported on TbNiSn and DyNiSn single crystals with the orthorhombic TiNiSi-type structure. Thermal variation of the electrical resistivity and magnetic susceptibility indicates the existence of three successive magnetic transitions at T 1 = 6.0K, T 2 = 7.6K and T N = 18.5 K in TbNiSn and two magnetic transitions at T 1 = 5.4K and T N = 7.3 K in DyNiSn. Magnetization up to 15 T along the b -axis at 1.6 K exhibits a four-step metamagnetic transition for TbNiSn and a three-step one for DyNiSn. High-field magnetization curves for TbNiSn in fields up to 30 T at 1.4K show unexpected small jumps, which may suggest a switching of the magnetic axis.

Orientation of red blood cells in high magnetic field

Abstract The orientation of red blood cells (RBCs) has been investigated in static high magnetic field. Normal RBCs are oriented with their disk plane parallel to the field. However, solidified RBCs are oriented with their disk plane perpendicular to the field direction. This change of orientation probably arises from the magnetic anisotropy of partially aligned hemoglobin molecules in a cell.

Biological systems in high magnetic field

Diamagnetic orientation of biological systems have been investigated theoretically and experimentally. Fibrinogen, one of blood proteins, were polymerized in static high magnetic fields up to 8 T. Clotted gels composed of oriented fibrin fibers were obtained even in a field as low as 1 T. Red blood cells (RBC) show full orientation with their plane parallel to the applied field of 4 T. It is confirmed experimentally that the magnetic orientation of RBC is caused by diamagnetic anisotropy. Full orientation is also obtained with blood platelet in a field of 3 T.