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Several studies are conducted to explain the impact of the different carbon nanotubes on the electromagnetic, as well as microwave absorbing properties of the [La.sub.0.7][Sr.sub.0.3][MnO.sub.3[delta]] (LSMO) composites. The permittivity of the complexes is shown to highly increase with the increase in CNT composition.

Several powder x-ray diffraction studies are conducted to explain the preparation and the large magnetic entropy changes taking place in the nanocrystalline [Pr.sub.0.7][Sr.sub.0.3]Mn[O.sub.3] compounds. The magnetic ordering of the compounds is shown to be of the second order nature.

A two-phase model is utilized to determine the field angle dependence of the coercive field of [La.sub.0.67][Sr.sub.0.33]Mn[O.sub.3] thin films grown epitaxially on NdGa[O.sub.3] substrates with different crystallographic orientations. The findings for angle dependence of the coercivity could be applied to better understand and possible engineering of the switching behavior of magnetic tunnel junctions.

The resistivity, magnetization, and magnetoresistivity of an [Nd.sub.0.43][Sr.sub.0.57]Mn[O.sub.3]/Y[Ba.sub.2][Cu.sub.3][O.sub.7] (NSMO/YBCO) heterostructure were measured to examine their proximity effects of superconductivity and antiferromagnetism. The evolution of superconducting transition temperature (Tc) and antiferromagnetic transition temperature ([T.sub.N]) with applied current density (J) and magnetic field (H) mark the profound effects of spin injection on destructing the superconductivity as well as the magnetic orders.

Magnetometry, x-ray, and neutron scattering are used for studying the structural and magnetic properties of a TbMn[O.sub.3] thin film grown on a [001] SrTi[O.sub.3] substrate by pulsed laser deposition. The results have shown that the ferromagnetism is an intrinsic property of the TbMn[O.sub.3] film.

The structural and magnetocaloric properties of the perovskite manganite [La.sub.2/3-x][Y.sub.x][Ca.sub.1/3-y][Sr.sub.y]Mn[O.sub.3] are analyzed. The ferromagnetic ordering temperature [T.sub.c] has increased abruptly due to the increase in the competition between A-site size-disorder degree and double-exchange interaction resulting from Mn-O-Mn bond angle and the phase transition is broadened due to the cation disordering at A-site.

The superconducting quantum interference device (SQUID) magnetization measurements are performed on single crystal manganites [La.sub.1-x][Sr.sub.x]Mn[O.sub.3]. The observed anomaly, which is reproduced in the temperature dependence of the NMR frequency, is attributed to a continual decrease in the exchange interaction within the temperature interval 60 K and the difference between [T.sub.MI] and [T.sub.oo] to an inherent inhomogeneity in Sr concentration.

The phase stability, nonstoichiometry, point defects, and magnetoresistance (MR) of polycrystalline [Sr.sub.2]FeMn[O.sub.6-[delta]] (SFMO) are analyzed. The variation of structural parameters, magnetization and MR is discussed in relation to oxygen nonstoichiometry [delta] and maximum MR if observed for samples with large [delta].

Magneto-optic measurements are used for studying the polarization of the mobile electrons in [La.sub.0.7][Sr.sub.0.3]Mn[O.sub.3] strained thin films grown epitaxially on single crystalline (001) LaAl[O.sub.3] (LAO) and (001) [La.sub.0.3][Sr.sub.0.7][Al.sub.0.65][Ta.sub.0.35][O.sub.9] substrates. The magnetic circular dichroism (MCD) spectra of both the films have shown a peak at the band gap at around 3 eV and the peak is shifted toward lower energy side with the increase in temperature.

The texture, microstructure and magnetotransport properties of c-axis oriented [La.sub.0.7][Sr.sub.0.3]Mn[O.sub.3] (LSMO) films on MgO-buffered Si[O.sub.2]/Si substrates are studied and compared to epitaxial LSMO/MgO (001) and polycrystalline LSMO/Si[O.sub.2]/Si films. The c-axis oriented LSMO films have displayed large low field magnetoresistance (LFMR) that is attributed to the spin-dependent scattering of transport current at the grain boundaries.

Single-phase epitaxial [La.sub.0.47][Ce.sub.0.20][Ca.sub.0.33]Mn[O.sub.3-[delta]] films on (001) SrTi[O.sub.3] are prepared by pulsed laser deposition and by reducing the oxygen pressure for deposition. The temperature dependence of the electrical resistance (R) of the single-phase films has obeyed the thermally activated behavior, the magnetic transition temperature has increased and R has decreased by annealing.

The effects of lanthanum efficiency on the structural and magnetic properties of manganites with normal composition [La.sub.0.7-x][Sr.sub.0.03]Mn[O.sub.3] prepared by sol-gel method with the highest heat treatment temperature are examined by using X-ray diffraction (XRD). The ion ratios are used in Rietveld fitting of the XRD spectra and the dependence of the Curie temperature on the content ratio [R.sub.M4] of [Mn.sup.4+] ions at B site is similar to that of the perovskite [La.sub.1-x][Sr.sub.x]Mn[O.sub.3].

Crystallographic, magnetic and electric properties of [Ca.sub.1-y][Sr.sub.y][Ru.sub.1-x][Mn.sub.x][O.sub.3] are examined. The enhancement of [T.sub.C] is because of the change in the crystal symmetry caused by the Sr substitution.

The structural, magnetic and electronic properties of SrTi[O.sub.3] capped [La.sub.2/3][Ca.sub.1/3]Mn[O.sub.3] electrodes grown on (001) and (110) SrTi[O.sub.3] substrates are studied. The studies have shown that electronic phase separation in the (001) electrodes are increased by the presence of the SrTi[O.sub.3] capping layer and the electronic state of interfacial Mn ions from (001) electrode is more sensitive to the capping layer.