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We report high-energy synchrotronX-ray diffraction spectrum andhigh-temperature magnetic data for multiwalled carbon nanotubes (MWCNTs)embedded with Fe and Fe3O4nanoparticles. Weunambiguously show that the saturation moments of the embedded Feand Fe3O4nanoparticles are enhanced by a factorof about 3.0 compared with what would be expected if they would beunembedded. More intriguingly the enhanced moments were completelylost when the sample was heated up to 1120 K, and the lost momentswere completely recovered through two more thermal cycles below 1020K. These novel results cannot be explained by the magnetism of theFe and Fe3O4impurity phases, the magnetic proximityeffect between magnetic nanoparticles and carbon, and the ballistictransport of MWCNTs. [ABSTRACT FROM AUTHOR]

Abstract: We present numerical calculations of the nuclear spin-lattice relaxation rate in the superconducting state of pure indium and slightly underdoped n-type cuprate Pr0.91LaCe0.09CuO4− y . By properly taking into account electron–phonon coupling, our calculated for the conventional s-wave superconductor, indium, is in quantitative agreement the experimental data with a clear Hebel–Slichter peak. In contrast, the absence of the Hebel–Slichter peak in the data of Pr0.91LaCe0.09CuO4− y can be explained by either d-wave or highly anisotropic s-wave gap symmetry. Thus, the absence of the Hebel–Slichter peak does not necessarily argue against an s-wave gap symmetry in this electron-doped cuprate. [Copyright &y& Elsevier]

Deals with a study that described a method for preparing single crystals of Ba[sub2]GdCu[sub3]O[sub7-y] of much larger size. Factors that were obtained from a superconducting crystal; Step taken to characterize the electrical quality of the annealed crystal; Cause of the large resistivity in the single crystal.

We report high-temperature magnetic measurements for SiO2-coated ultrafine Fe3O4 nanoparticles. The Curie temperatures of the ultrafine Fe3O4 nanoparticles are significantly reduced and follow a finite-size scaling law predicted from Monte Carlo simulations. Our current result provides the first quantitative confirmation of the finite-size scaling law for quasi-zero-dimensional magnetic systems. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic measurements have been performed on 40-nm sphere-like Fe3− δ O4 () nanoparticles using a Quantum Design vibrating sample magnetometer. Coating Fe3− δ O4 nanoparticles with SiO2 effectively eliminates magnetic interparticle interactions so that the coercive field in the high-temperature range between 300 K and the Curie temperature (855 K) can be well fitted by an expression for noninteracting randomly oriented single-domain particles. From the fitting parameters, the effective anisotropy constant K is found to be , which is very close to the bulk magnetocrystalline anisotropy constant of . Moreover, the inferred mean particle diameter from the fitting parameters is in quantitative agreement with that determined from transmission electron microscope. Such a quantitative agreement between data and theory suggests that the ensemble of our SiO2-coated sphere-like Fe3− δ O4 nanoparticles represents a good system of noninteracting randomly-oriented single-domain particles. [Copyright &y& Elsevier]

Abstract: We report magnetic properties of silica-coated CoFe2O4 nanoparticles (about 32 nm) in a wide temperature range (4–700 K). Coating CoFe2O4 nanoparticles with amorphous silica yields an assembly of noninteracting single-domain particles with cubic magnetocrystalline anisotropy. We find that the reduced remanence is about 0.81–0.82 at low temperatures (), very close to the theoretical prediction (0.83) for cubic anisotropy. The room-temperature anisotropy constant inferred from the data is also in quantitative agreement with the bulk value (). The current work thus provides a quantitative test for a theory of noninteracting single-domain particles with cubic anisotropy. [Copyright &y& Elsevier]

We reanalyze specific heat data for optimally electron-doped Pr(1.85)Ce(0.15)CuO(4-y) superconductors. The magnetic field dependence of the electronic specific heat in the vortex state does not support d-wave gap symmetry but agrees quantitatively with an s-wave theory. Furthermore, the field dependence at a finite temperature almost coincides with that for a conventional s-wave superconductor, Vi(3)Si. The present work provides bulk evidence for a nodeless s-wave gap symmetry in optimally electron-doped cuprates.