Metamagnetic and electronic transitions in charge-ordered Nd0.50Ca0.47Ba0.03MnO3 manganite

The ABO3 type charge-ordered antiferromagnetic Nd0.50Ca0.50MnO3 (NCMO) manganite is doped at A-site by 3 % of Ba2+ for Ca2+. The resulting system, Nd0.50Ca0.47Ba0.03MnO3 (NCBMO), is studied for the effects of Ba doping on the magnetic and electronic properties. On application of magnetic field to NCBMO, strongly correlated successive sharp metamagnetic and electronic transitions are observed from antiferromagnetic-insulating to ferromagnetic-metallic state at 2.5 K. The critical magnetic field (Hc) required for metamagnetism is found to reduce drastically from 15 T for undoped NCMO to 3 T for NCBMO. On increasing the temperature, the Hc of NCBMO passes through a minimum. This behavior of Hc of NCBMO contrasts to that of NCMO. The results are discussed in context of A-site cation disorder and size

Studies on La2-xPrxCayBa2Cu4+yOz (0.1 < x < 0.5) type mixed oxide superconductors

The La2-xPrxCayBa2Cu4+yOz (LaPrCaBCO) mixed oxides have been studied for their structural and superconducting properties using X-ray diffraction (XRD), d. c. resistivity, d. c. susceptibility and iodometric double titration. All the LaPrCaBCO samples for x = 0.1 - 0.5, exhibit tetragonal crystalline structure with P 4/mmm space group as determined by Rietveld analysis of the X-ray diffraction data. With increasing x, enhancement in Tc is observed, which is quite interesting for Pr substituted high Tc oxides. Maximum Tc ~ 58 K has been observed for x = 0.5(La-2125 stoichiometry). The results of structural studies and superconducting property measurements are presented in light of increase in Tc in LaPrCaBCO system with increasing Pr concentration.Comment: 6 pages including 5 figures and 1 tabl