La2CoMnO6 perovskite manganite was synthesized by solid-state reaction. Rietveld refinement of powder x-ray diffraction data indicated that this compound crystallized with an orthorhombic structure containing distorted (Co/Mn)O6 octahedra (Pnma; a = 5.5 Å; b = 7.2 Å; c = 5.4 Å. The dc magnetization and real part (x′) of the ac susceptibility were measured at dc fields up to 1 T and an ac field of 0.1 Oe at frequencies of 21, 217, 600 and 2000 Hz over a wide range of temperatures from 300 K down to 4.2 K. A ferromagnetic transition was observed at Tc = 220 K. A spin glass ground state was also determined from the shift of a peak at 220 K in the real part of the ac susceptibility with frequency and slow spin relaxation for T < Tc as indicated by the time dependence of the remanent magnetization. The spin glass state arises from a ferromagnetic state and might be caused by competition between the ferromagnetic and antiferromagnetic interaction.

In this letter, we report the results of transport J c of solenoid coils upto 100 turns fabricated with Cu-sheathed MgB 2 wires using a wind-reaction in-situ technique. Despite the low density of single core and some reaction between Mg and Cu-sheath, our results demonstrate the decrease in transport J c with increasing length of MgB 2 wires is insignificant. Solenoid coils with diameter as small as 10 mm can be readily fabricated using a wind-reaction in-situ technique. The J c of coils is essentially the same as in the form of straight wires. A J c of 133,000 A/cm 2 and 125,000 A/cm 2 at 4K and self field has been achieved for a small coil wound using Cu-sheathed tape and Cu-sheathed wire respectively. These results indicate that the MgB 2 wires have a great potential for lage scale applications

High critical current density is essential for most large-scale applications of high-temperature superconductors (HTSs). In addition to the weak link problem, weak flux pinning is a major cause of the rapid decline of with magnetic field at high temperatures. Through intensive research in the past 10 years the weak pinning problem has been partially overcome and has reached a level approaching the requirement for some commercial applications. In this article, a number of techniques by which effective pinning centres can be introduced to improve flux pinning in Bi - (Pb) - Sr - Ca - Cu - O HTSs are reviewed. These include surface pinning through a spiral growth, fine precipitates produced through phase transformation or phase formation - decomposition, inclusions through chemical doping or addition, cascades and columnar defects created by fast-neutron and heavy ion beam irradiation and various defects induced by mechanical deformation. In particular, the results of Bi-2223 formation - decomposition and cold deformation versus hot deformation have a significant implication for HTS wire fabrication. Comparative studies with comprehensive electrical, magnetic and microstructural characterizations have been carried out to assess the effectiveness of these techniques.

, J. M. (2013). Orbital structure of FeTiO3 ilmenite investigated with polarization-dependent X-ray absorption spectroscopy and band structure calculations. Applied Physics Letters, 102 (4), 042107-1-042107-4.

La0.8Sr0.2Mn1−xZnxO3 perovskite manganite with x = 0, 0.01, 0.03, 0.05, 0.1, 0.15, 0.3, 0.5 and 0.75 has been prepared by the solid state reaction and investigated by structural, transport and magnetic measurements. The structural characterization of the samples has been done by x-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. The x-ray powder diffraction results indicate a single phase for 0 < x < 0.5, confirming that zinc is incorporated on the Mn site. The lattice parameters (a, b, c) of this orthorhombic system increase with increasing zinc concentration in the system. According to the SEM images, the grain size of the materials with x > 0.1 decreases with increasing zinc doping levels. The transport measurements show that the insulator-to-metal transition temperature, Tc, decreases with increasing zinc substitution on the Mn site, and the resistivity increases. The Tc variations agree with the magnetic measurement data for x < 0.3. The compound changes from ferromagnetic to paramagnetic for x > 0.3. The possible mechanism behind the effects of zinc doping into the La0.8Sr0.2Mn1−xZnxO3 system involves degradation of the double exchange between Mn3+–O–Mn4+ in this compound.