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The crystal and magnetic structure of polycrystalline La 0.5− x Nd x Ca 0.5 MnO 3 ( 0.0 ≤ x ≤ 0.5 ) samples have been investigated using magnetization, resistivity, transmission electron microscope, and neutron diffraction techniques. The samples are isostructural and possess orthorhombic structure in Pnma space group. On lowering of temperature, the samples exhibit CE-type antiferromagnetic structure coexisting with a weak ferromagnetic ordering. The charge and orbitally ordered antiferromagnetic phase is weakened by the growth of ferromagnetic phase. The evolution of structural distortions and magnetic structure at low temperature as a function of Nd doping exhibit a strong correlation with A-site disorder ( σ 2 ) .

The present study reports the effect of swift heavy ion irradiation on structural and magnetic properties of sputtered W/Fe multilayer structure (MLS) having bilayer compositions of [W(10 A)/Fe(20 A)]10BL. The MLS is irradiated by 120 MeV Au9+ ions of fluences 1×1013 and 4×1013 ions/cm2. Techniques like X-ray reflectivity (XRR), cross-sectional transmission electron microscopy (X-TEM) and DC magnetization with a vibrating sample magnetometer (VSM) are used for structural and magnetic characterization of pristine and irradiated MLS. Analysis of XRR data using Parratt’s formalism shows a significant increase in W/Fe layer roughness. X-TEM studies reveal that intra-layer microstructure of Fe layers in MLS becomes nano-crystalline on irradiation. DC magnetization study shows that with spacer layer thickness interlayer coupling changes between ferromagnetic to antiferromagnetic.

In the present study we report the precise resistivity measurements for the polycrystalline bulk sample as well as highly oriented thin-films of La 0.8 Ca 0.2 MnO 3 . The poly crystalline sample was prepared by standard solid-state reaction route and the oriented thin film was prepared by pulsed laser deposition (PLD). The phase purity of these samples was confirmed by X-ray diffraction and the back-scattered electron imaging using scanning electron microscopy (SEM). The oxygen stoichiometry analysis was done by iodimetry titration. The resistivities of these samples were carried out with four-probe resistivity measurement setup. The observed temperature dependence of resistivity data for both the samples was fitted using the polaron model. We have found that polaronic model fits well with the experimental data of both polycrystalline and single crystal samples. A new phenomenological model is proposed and used to estimate contribution to the resistivity due to grain boundary in the ferromagnetic state of polycrystalline manganites and it has been shown that the scattering of electrons from the grain boundary (grain surface) is a function of temperature and controlled by the effective grain resistance at that temperature.