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Abstract: The yttrium iron garnet (YIG) has been intensively studied in the past as a convenient ferrimagnetic insulator for resonance devices and magnetic memories. The YIG was considered as the model of ionic compound with the ion Fe3+ and 5μB on each of two iron sites with a resulting magnetization of 5μB. Contrarily, all neutron diffraction studies lead to a localized moment close to 4μB. The present work is a tentative to understand these noticeable discrepancies by using the electronic structure computing. [Copyright &y& Elsevier]

Abstract: Pure YBa2Cu3O7−δ (YBCO) pellet and many pellets of YBa2Cu3O7−δ /Y3Fe5O12 (YBCO/YIG) of different concentrations of YIG were prepared by pressing nanoparticles into disks of 5mm of diameter and 0.5mm of thickness. X-ray diffraction (XRD) with CoKα radiation was used to check the phase formation and to determine the mean crystallite sizes from the half-width X-ray peaks using the Scherrer relation. Magnetization measurements vs. temperature T and applied field H were performed using a conventional magnetometer within the temperature range 4.2–110K and in magnetic fields up to 10T. The field was applied parallel to the pellet axis. Our results confirm the superconductivity and ferromagnetism coexistence in nanoparticles of YBCO at 4.2K. For H less than a threshold field H ⁎, the superconducting nano-domains are prevalent in the sample. When the field increases beyond H ⁎, the spins of the superconducting nano-domains line up along the direction of the applied field to create a ferromagnetism phase that reinforces the ferromagnetic nano-domains. The present experimental findings corroborate Kopp et al.'s claims that superconductivity and ferromagnetism in singlet superconductors such as cuprates do not exist uniformly but are phase-separated in nano-domains. [Copyright &y& Elsevier]

Since the solid matter in our solar system began to assemble 4.57 billion years ago, meteorites have recorded a large range of processes, including metamorphism, melting, irradiation and hypervelocity impacts. These processes as well as solar system magnetic fields can be accessed through the investigation of magnetic properties of meteorites. In this work, we present magnetic hysteresis properties, isothermal remanent magnetization acquisition curves and 57 Fe Mössbauer spectra for nineteen iron and eleven stony-iron meteorites. These data will be the background for a discussion about the thermal and shock history of these meteorites. Although Mössbauer spectroscopy and hysteresis measurements are not able to provide cooling rates like the conventional metallographic method does, we show that the combination of the ordering degree of taenite phase measured by Mössbauer spectroscopy and hysteresis properties are useful for constraining the thermal and shock history of meteorites. In particular, strong shock and the associated thermal event that result in disordering of tetrataenite can be easily identified. [ABSTRACT FROM AUTHOR]

Abstract: Amorphous (Fe50Co50)62Nb8B30 powder mixture was prepared by mechanical alloying from elemental Fe, Co, B and Nb powders in a planetary ball mill under argon atmosphere. Structural, thermal and magnetic properties were performed on the milled powders by means of X-ray diffraction, differential scanning calorimetry and magnetic measurements. The amorphous state is reached after 125h of milling. The excess enthalpy due to the high density of defects is released at temperature below 300°C. Crystallisation and growth of crystal domains are the dominating processes at high temperatures. The saturation magnetisation decreases rapidly during the first 25h of milling to about 15.24Am2/kg and remains nearly constant on further milling. Coercivity, H c, value of about 160Oe is obtained after 125h of milling. [Copyright &y& Elsevier]