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Magnetization measurements have been performed on samples composed of oriented YBa 2 Cu 3 O 7 single crystals 1.4 K, 68 K and 78 K in magnetic fields up to 38 T applied along the c -axis and within the ab -plane. The critical currents are deduced from the irreversible magnetization and discussed in terms of pinning forces. At low temperature (1.4 K), the experimental data with the field along the c -axis are compared with a theoretical model for the field dependence of the pinning force. At higher temperatures (68 K and 78 K), the pinning force can be described by a Kramer-like scaling law: F p = A [ B 0 ( T )] m b p (1− b ) q , where B 0 is the field where the irreversibility of the magnetization disappears and where b (= B / B 0 ) is the reduced field. For the exponent m , the usual value of 2.5 is found; approximate values for p and q are around 2 and 4, respectively.

De-Haas-van Alphen (DHVA) frequencies corresponding to the neck orbits of a majority-spin Fermi surface have been observed over a wide range of orientations in the ferromagnetic FCC alloy Co0.92Fe0.08. Self-consistent band-structure calculations can largely explain the experimental results, albeit that the predicted neck diameter is 20% too small.

Two constraints on semi-continuous magnet coils are the strength of the winding material, and the maximum power which the rectifier must deliver for a short time. Here we assume that for a 60-T coil wire of sufficient strength (about 100 kg/mm2 is available. It was shown earlier that a single, homogeneous coil needs a power of nearly 150 MW, which calls for huge capital investments in power lines, transformers, switches and rectifiers. By using two nested coils, wound from wires with different strengths and current densities, and energized successively by the same rectifier, we can reduce the power to less than 50 MW.

The zero-field moment of Tb has been determined at 4.2 K for a very pure single crystal along the b direction. A value of (9.490 ± 0.010) μ B /at was found. The corresponding conduction electron polarization of 0.519 μ B /at is much higher than previously estimated. The conduction electron susceptibility was found not to be at variance with the value obtained from band calculations. No agreement is found for the field dependence of the magnetization at 64.5 K and 77 K with a renormalized spin wave theory although the differences are small.

The zero field moment of Gd has been measured at 4.2K for a single crystal prepared by solid state electrotransport. It is magnetically very soft: the moment is (7.630+or-0.010) mu B per atom in the b direction and is slightly smaller in the c direction. The conduction electron polarization is 15% higher than previously estimated. Due to its small value the conduction electron susceptibility could not be measured accurately.

High field (30 MA m-1) magnetization measurement at 4.2K and 20.4K on samarium single crystals are reported together with low field studies from 1.8K to 130K. The susceptibility results are analyzed in terms of independent contributions from the moments on the cubic and hexagonal sites (which order antiferromagnetically at 14K and 109K respectively), plus a temperature independent susceptibility. At 4.2K a spin-flop transition on the cube sites was observed around 21.6 MA m-1. Using one anisotropy and two exchange parameters a molecular field model correctly describes the main features of the behaviour on the cubic sites, and their saturation moment is calculated to be 0.47 mu B/atom.

A sample of YBa 2 Cu 3 O 7 was constructed by stacking a number of small single crystals. Magnetization measurements were made in magnetic fields up to 38 T, both parallel to the c -axis and to the basal plane. At 1.4, 4.2 and 20.4 K, a large irreversible magnetization was observed. The significance of these results for the superconducting properties is discussed.

The Fermi surface of Nb/sub 3/Sn has been derived from an APW band calculation. de Haas-van Alphen (dHvA) oscillations have been observed in Nb/sub 3/Sn and V/sub 3/Si which give a consistent FS description. Using single crystals of high resistance ratio's and magntic fields up to 400 kOe, dHvA oscillations have been seen in the normal state for both specimens. New features of the Fermi surface include osculated ellipsoidal structure around M and a large cubical structure around LAMBDA.

The magnetization of bismuth single crystals has been measured in very high magnetic fields up to 340 kG. Along the binary and the bisectrix axes the data (at 1.5 K) show small but significant deviations from linearity, but along the trigonal axis the deviation is much smaller and barely significant.

The magnetization of high- T c superconducting REBa 2 Cu 3 O 7 compounds, where RE is Y or one of the rare-earth elements Eu, Gd, Dy, Ho, Er or Yb, has been measured in fields up to 29 T. Though the precise analysis of the data is hampered by the incomplete penetration of the magnetic field due to the shielding-current effect of the superconductivity, the magnetism associated with the rare-earth ions can reasonably be interpreted by crystal-field effects. All of the samples investigated were confirmed to be superconducting at 4.2 K in fields as high as 29 T.

The de Haas-van Alphen (DHVA) effect has been investigated in Pd and Pd-Ni alloys in magnetic fields extending to 40 T. With increasing Ni content, the incipient ferromagnetism gives rise to an unusual behaviour which is dominated by a field dependence of the Stoner factor.

de Haas-van Alphen frequencies in the (100) and (110) planes of Nb3Sn have been measured with a typical accuracy of 1%. Several frequency branches have been found between 100 and 1000 T. Effective masses corresponding to some of the orbits at symmetry directions have been estimated from the experiments. A pronounced anisotropy ( approximately 10%) in the upper critical field was observed. The magnitude of the critical field was found to be sample dependent. The DHVA data are interpreted using self-consistent new ASW band-structure calculations which include tetragonal distortion of the unit cell.

de Haas-van Alphen (dHvA) oscillations have been observed in ${\mathrm{Nb}}_{3}$Sn in the (110) plane and in ${\mathrm{V}}_{3}$Si at two orientations using single crystals of high resistance ratio and magnetic fields in excess of ${H}_{c2}$. The dHvA frequency data for ${\mathrm{Nb}}_{3}$Sn can be interpreted as a series of nested ellipsoids centered at $M$, as suggested by a recent high-precision calculation of the ${\mathrm{Nb}}_{3}$Sn Fermi surface.

Magnet coils are investigated which can produce magnetic fields of 15–40 MA/m (200–500 kOe) during working times of the order of 0.1 sec. These fields are suited for measurements in highly conducting materials. The coils are precooled to 20°K or 77°K and the Joule heat is not removed during the pulse. In Sec. I the thermal limitations of this method are reviewed. Plots are given for the optimum dimensions and current densities for coils producing a specified field during a specified time, minimizing the necessary power supply. Details of a magnet constructed along these lines are given. The maximum field produced by this coil, 16 MA/m (200 kOe) during 0.3 sec, however, proved to be determined by mechanical instabilities. These problems are reviewed in Sec. II. Calculations of the Lorentz force and the internal stresses resulting from it were carried out taking the elastic and plastic properties of copper and insulation into account. It is shown theoretically that a magnet stable to 35 MA/m (440 kOe) can be built from hard drawn copper if a reinforcing steel cylinder is used at a certain radius inside the coil.

The University of Amsterdam has a semicontinuous magnet in operation, which can generate fields up to 40 T and keep these fields constant (within 1:10/sup 4/) during 0.1 s for 40 T, and longer for lower fields. The authors discuss a project for the establishment of a 60-T 100-ms facility primarily based on the concept of the present 40 T 100-ms magnet with its controlled power supply, which makes, within certain limits, any desired field profile possible. A Cu-Be mantle with a core of pure Cu is the most-suitable candidate for the wire material of the 60 T coil. The power supply, rectifier, transformers, and thyristors needed are described. The prospects for the fulfilment of the design are briefly mentioned. >

An overview is given of the high-field installation of the University if Amsterdam now in operation; this installation can generate fields up to 40 T, constant within 8 mT for about 80 ms. Recent improvements of the regulation of the field are discussed, as well as some examples of recent measurements.

The magnetization of NdAl 2 single crystals was measured at 4.2, 20.3 and 77 K, in magnetic fields up to 35 tesla applied in the 〈100〉, 〈110〉 and 〈111〉 directions. The magnetization in these directions may be described theoretically, without any fitting, in terms of two cubic crystalline electric field parameters and one molecular field constant which have been taken from inelastic neutron scattering data. 5

The non-linear part of the magnetisation of pure Pd and dilute PdNi alloys (up to 0.56 at.% Ni) was measured in semi-continuous fields up to 35 T. The Ni-doped Pd shows a negative curvature at high fields whilst for pure Pd a small positive curvature was found as in previous measurements. In the alloys the curvature becomes more pronounced for higher Ni concentrations. These effects and their relation to recent DHVA measurements are discussed in this article.

The magnetoresistance of Gd single crystals has been investigated from 4.2 to 220 K, and in fields up to 35 T, in both longitudinal and transverse configurations. At low temperatures the magnetoresistance is positive, due to electron trajectory effects, whilst above 50 K the negative magnetoresistance arising from the suppression of spin fluctuation is evident. The anisotropy between longitudinal and transverse configurations is discussed.

Magnetization measurements in pulsed magnetic fields up to 40 T at 1.3, 67 and 78K have been performed on a 50 mg sample composed of 45 aligned single crystals of YBa2Cu3O7. Data have been obtained with the applied field both parallel and perpendicular to the c axis. The results are compared with dc magnetization measurements on the same sample. At high temperature a strong dependence on the field sweep velocity is observed. The results are discussed in terms of flux pinning and thermally activated flux-flow.

Hall-effect of single-crystalline UPt 3 and U(Pt 0.95 Pd 0.05 ) 3 was measured in magnetic fields up to 38 T. At all investigated temperatures R H is found to decrease with increasing field; at 1.4 and 4.2 K a large peak is found that is attributed to the suppression of antiferromagnetic correlations.

De Haas-van Alphen oscillations have been observed in the magnetization of a power sample of ln3 Yb and are ascribed to a small spherical part of the Fermi surface.

The non-linearity of the magnetization of Pd at 4.2°K has been determined in semi-continuous fields up to 325 kOe. The value of β in the expression M = χ H (1 + βH 2 ) is found to be positive, β = (9.5 ± 1.7) × × 10 −18 m 2 /A 2 ≙ 6 × 10 −14 Oe −2 .