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Some materials can exhibit the properties of ferromagnetism amd superconductivity, but both long-range states are normally mutually exclusive. A new study of the compound TmNi2B2C investigates the effect of small-angle neutron scattering which reveals that the symmetry of the flux-line lattice and the magnetic modulation are strongly coupled.

Metamagnetic transitions in single-crystal rare-earth nickel borocarbide Ho[Ni.sub.2][B.sub.2]C and Er[Ni.sub.2][B.sub.2]C at T=1.9 K is studied with a Quantum Design torque magnetometer. Torque measurements of the Er borocarbide clearly show that the sequence of metamagnetic transitions with increasing field depends on the angular direction of the magnetic field relative to the easy axis.

It has been possible to undertake dc magnetization calculations, for zero-field cooled and field-cooled scenarios, for flash-evaporated Pd-doped NiMn thin films. This work appears to favour the Imry-Ma model to explain the unusual irreversibility effect seen in the NiMn system.

A new study investigates the effect of doping Mn in Bi-Pb-Sr-Ca-Cu-O to ascertain its effect on phase formation and transition, and electrical resistivity.

Experimental measurements of the resistivity of metallic glass Fe70Ni12B16Si2 indicate that replacement of nickel with molybdenum alters the resistivity of the glass for temperatures between 1.5 K and 300 K. The influence of temperature on the normalized resistivity of the glass changes with increasing Mo levels. The resistivity of molybdenum-substituted glass coincides with that of Cr-substituted glass. Mo activates an 'interaction' like Cr, in the glass.

The superconducting properties of lead bismuth ([Pb.sub.82][Bi.sub.18]) films in a spatially varying magnetic field created by a hybrid structure of soft magnetic and nonmagnetic layers perpendicular to the superconducting film surface are described. The results have shown that the critical current [I.sub.C] and the second critical field [H.sub.C2] can be increased by the simple redirection of magnetic flux with a soft magnetic microstructure.

Magnetic and thermodynamic measurements for [R.sub.5]Ni[Pb.sub.3] (R=Ce, Nd, Gd) are described. Nonmagnetic [La.sub.5]Ni[Pb.sub.3] is used for isolating the magnetic heat capacity for all three materials and the results have included a relatively large linear-T term in the specific heat and integrated magnetic entropies consistently smaller than expected.

Metamagnetic transitions in single crystal Tb[Ni.sub.2][B.sub.2]C are studied at 1.9 K with a Quantum Design torque magnetometer. Torque magnetometry has not only shown a different sequence of metamagnetic phases for fields near the easy axis from those near the hard axis, but also the different natures of a principal metamagnetic phase near the hard axis.

The metamagnetic transitions in single-crystal Er[Ni.sub.2][B.sub.2]C are studied with Quantum Design torque magnetometer. The results have shown new metamagnetic states in Er[Ni.sub.2][B.sub.2]C.

Magnetic, thermal and transport properties of NdNiPb and [Nd.sub.5]Ni[Pb.sub.3] and their crystalline electric field (CEF) splitting effects are examined. [Nd.sub.5]Ni[Pb.sub.3] has displayed a ferrimagnetic transition, whereas NdNiPb has displayed an antiferromagnetic phase transition associated with the alignment of crystal-field-split levels of the magnetic Nd ion and transport properties closer to those of a classic metallic system.

Electrical resistivity, heat capacity and dc magnetization measurements are performed on the Al[B.sub.2]-type intermetallics NdCuGe and LaCuGe over a wide temperature range. Simple-metallic behavior has provided a good fit to the NdCuGe thermopower and hence the CeCuGe results are attributed to resonant scattering due to partial hybridization of the localized orbitals.

Samples of RuSr2([Gd.sub.(1.5)][Ce.sub.(0.5)])Cu2[O.sub.(10-delta)] were prepared and annealed in pure oxygen at 30, 62 and 78 atm. A low-temperature Schottky-type anomaly was found in their heat capacity below 20 Kelvin, which can be attributed to splitting of the ground [[.sup.8.S].sub.7/2] of paramagnetic [Gd.sup.3+] ions.

The magnetic and thermodynamic properties of [Nd.sub.2][Ni.sub.2]Pb are investigated. The heat capacity measurements indicate an antiferromagnetic phase transition at 19-Kelvin involving crystal-field-split levels and magnetization measurements confirm a spin-alignment metamagnetic transition at 3 T.

Transport, magnetic, magneto-optical (Kerr effect) and optical (light absorption) properties are studied in an oriented polycrystalline La0.67Ca0.33MnO3 film that shows colossal magnetoresistance. A giant change in infrared light transmission is observed on crossing the Curie temperature (about 270 K) from high to low temperature.

The effect of crystal lattice disorder on the conductivity and colossal magnetoresistance in La1-xCaxMnO3 ( ) films has been examined. The lattice defects are introduced by irradiating the film with high-energy ( MeV) electrons with a maximal fluence of about cm-2. This comparatively low dose of irradiation produces rather small radiation damage in the films. The number of displacements per atom (dpa) in the irradiated sample is about 10-5. Nevertheless, this results in an appreciable increase in the film resistivity. The percentage of the resistivity increase in the ferromagnetic metallic state (below the Curie temperature ) was much greater than that observed in the insulating state (above ). At the same time irradiation has much less effect on or on the magnitude of the colossal magnetoresistance. A possible explanation of such behavior is proposed. [ABSTRACT FROM AUTHOR]

Abstract: The metamagnetic transitions in single-crystal rare-earth nickel borocarbide ErNi2B2C and TbNi2B2C have been studied at 1.9K with a Quantum Design torque magnetometer. The critical fields of the transitions depend crucially on the angle between applied field and the easy axis [100]. Torque measurements have been made while changing angular direction of the magnetic field (parallel to basal tetragonal ab-planes) in a wide angular range (more than two quadrants). The results obtained permit discovery of new features of the metamagnetic states in these compounds, which were not revealed in previous studies. For both borocarbides the sequences of metamagnetic transitions with increasing field were different for the magnetic field along (or close enough to) the easy [100] axis from that near the hard [110] axis. [Copyright &y& Elsevier]