With pulsed laser deposition we have grown c-axis oriented thin films of the nominal composition LaMnO 3 (LMO) on LSAT(001) substrates. We find that, depending on the oxygen background pressure during growth, the LMO films contain sizeable amounts of La and/or Mn vacancies that strongly influence their electronic and magnetic properties. Specifically, we show that the Mn/La ratio can be systematically varied from 0.92 at 0.11 mbar to 1.09 at 0.30 mbar of oxygen.These cationic vacancies lead to markedly different disorder effects that become most pronounced once the samples are fully oxygenated and thus strongly hole doped. All as-grown and thus slightly oxygen deficient LMO films are ferromagnetic insulators with saturation moments in excess of 2.5  Bper Mn ion, their transport and optical properties can be understood in terms of trapped ferromagnetic polarons. Upon oxygen annealing, the most La-deficient films develop a metallic response with an 39

We report studies of the ferroelectric and magnetic phase transitions of (1 – x)­Pb­(Fe0.5Nb0.5)­O3 – xCo0.65Zn0.35Fe2O4 (x = 0.2) composite with emphasis upon the nature of magnetoelectric coupling at room temperature. The presence of all cationic elements with their required stoichiometry have been confirmed by SEM and XPS studies. The composite shows well-saturated ferroelectric and ferromagnetic (multiferroic) behavior at room temperature. A ferroelectric-paraelectric phase transition has been confirmed from the temperature dependent dielectric spectra along with DSC and Raman spectroscopic studies. Antiferromagnetic, ferromagnetic, and relaxor paramagnetic states have been observed in this composite. This composite shows strong bulk biquadratic magnetoelectric coupling at room temperature, which can be useful for potential multifunctional device applications.

Multiferroic composite structures, i.e., composites of magnetostrictive and piezoelectric materials can be envisioned towards the goal of achieving strong room-temperature ME coupling for real practical device applications. Magnetic materials with high magnetostriction, high Néel temperature (TN), high resistivity and large magnetization are required to observe high ME coupling in composite structures. In continuation to our investigations for suitable magnetic candidate for multiferroic composite structures, we have studied the crystal structure, dielectric, transport, and magnetic properties of Co0.65Zn0.35Fe2O4 (CZFO). Rietveld refinement of X-ray diffraction patterns confirms the phase purity with cubic crystal structure with (Fd 3 m) space group; however, we have found a surprisingly large magnto-dielectric anomaly at the Neel temperature, unexpected for a cubic structure. The presence of mixed valences of Fe +2 /Fe +3 cations is probed by X-ray photon spectroscopy (XPS), which support the catonic ordering-mediated large dielectric response.Large dielectric permittivity dispersion with a broad anomaly is observed in the vicinity of the magnetic phase transition temperature (TN) of CZFO suggest the strong correlation 2 between dielectric and magnetic properties. The ferromagnetic-paramagnetic phase transition of CZFO has been found ~640 K, which is well above room temperature. CZFO exhibits low loss tangent, high dielectric constant and large magnetization with soft magnetic behavior above room temperature. We describe the possible potential candidates for multiferroic composite structures as well as for multifunctional and spintronics device applications.

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