Growth and Structural Characterization of -LuMnO Thin Films Deposited by Direct MOCVD.

In this work, we investigated the MOCVD conditions to synthesize thin films with the hexagonal -LuMnO phase as a potential low-band gap ferroelectric material. The main parameters investigated were the ratio of organometallic starting materials, substrate temperature, and annealing effect. Two different substrates were used in the study: fused silica (SiO) glass and platinized silicon (Pt\Ti\SiO\Si(100)).

Effects of Substitution and Substrate Strain on the Structure and Properties of Orthorhombic EuYMnO (0 ≤ x ≤ 0.5) Thin Films.

The effects on the structure and magnetic properties of EuYMnO (0.0 ≤ x ≤ 0.5) thin films due to lattice strain were investigated and compared with those obtained in equivalent composition ceramics.

Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO Thin Films.

Zirconia- and hafnia-based thin films have attracted tremendous attention in the past decade because of their unexpected ferroelectric behavior at the nanoscale, which enables the downscaling of ferroelectric devices. The present work reports an unprecedented ferroelectric rhombohedral phase of ZrO that can be achieved in thin films grown directly on (111)-Nb:SrTiO substrates by ion-beam sputtering. Structural and ferroelectric characterizations reveal (111)-oriented ZrO films under epitaxial compressive strain exhibiting switchable ferroelectric polarization of about 20.

Site Redistribution, Partial Frozen-in Defect Chemistry, and Electrical Properties of Ba1-x(Zr,Pr)O3-δ.

Changes in nominal composition of the perovskite (ABO3) solid solution Ba1-x(Zr,Pr)O3-δ and adjusted firing conditions at very high temperatures were used to induce structural changes involving site redistribution and frozen-in point defects, as revealed by Raman and photoluminescence spectroscopies. Complementary magnetic measurements allowed quantification of the reduced content of Pr. Weak dependence of oxygen stoichiometry with temperature was obtained by coulometric titration at temperatures below 1000 °C, consistent with a somewhat complex partial frozen-in defect chemistry.

Local bias induced ferroelectricity in manganites with competing charge and orbital order states.

Perovskite-type manganites, such as Pr1-xCaxMnO3, La1-xCaxMnO3 and La1-xSrxMnO3 solid solutions, are set forth as a case study of ferroelectricity formation mechanisms associated with the appearance of site- and bond-centered orbital ordering which breaks structural inversion symmetry. Even though the observation of macroscopic ferroelectricity may be hindered by the finite conductivity of manganites, polarization can still exist in nanoscale volumes. We use Piezoresponse Force Microscopy to probe local bias induced modifications of electrical and electromechanical properties at the manganite surface.