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We report the results of the structural, transport and magnetotransport studies on mono-valent doped La1-xNaxMnO3 (LNMO) (x = 0.05, 0.1 and 0.15) manganites. XRD measurement and Rietveld refinement on LNMO samples shows that, all the samples crystallize in distorted rhombohedral structure without any additional impurity peaks. The d.c. four probe resistivity measurements show that, the metal-insulator transition temperature (TP) exhibited by the Na doped manganites increases and resistivity decreases with increasing x. This behavior has been explained on the basis of size disorder effect, tolerance factor variation and structural modifications due to large size mono-valent Na-doping. In the metallic region, the resistivity data have been fitted to the zener double exchange (ZDE) polynomial law for all the three samples. Magnetoresistance (MR) studies show a decrease in low temperature (5K) MR while increase in room temperature MR with increase in Na-content in the LNMO manganites.

Bond Valence Sum (BVS) calculations were performed on neutron diffraction (ND) data measured at 12, 35, 55, 75 and 300 K on one sample (x = 0.3), of a series of La2-xDyxCa2xBa2Cu4+2xOz (La-2125) compounds. ND experiments have been carried out to study the effect of temperature on structure and to relate it with the superconducting properties. The sample, La1.7Dy0.3Ca0.6Ba2Cu4.6Oz (LD3) has been reported earlier, and exhibits superconductivity at 68 K. In this paper we discuss BVS calculations carried out on low temperature neutron diffraction data.

Epitaxial bilayers of YBa2Cu3O7-δ (YBCO) and La0.67Ca0.33MnO3 (LCMO) heterostructures have been prepared by pulsed laser deposition technique, the growth sequence being YBCO on LCMO. The length scale of the YBCO layer, which is rendered non-superconductor/insulator by selfinjection of the spin polarized quasiparticles, is estimated to be 850Å. This can be an important guiding parameter in spintronic device configuration/fabrication.