Analysis of Ferromagnetic-Multiferroic Interfaces in Epitaxial Multilayers of LSMO and BFO

Bilayers were fabricated from ferromagnetic LSMO (Lanthanum Strontium Manganate Oxide, La0.7Sr0.3MnO3) and ferroelectric BFO (Bismuth Ferrite, BiFeO3) using pulsed laser deposition in the presence of O2 on LaAlO3and SrTiO3 substrates. The layer thickness and the layer order were varied among 16 samples. The bilayers were analyzed using TEM, XRD, XRR, and XPS to determine the stoichiometry, interlayer diffusion, roughness, and other structural features. TEM imaging showed that portions of the bilayers were highly crystalline. However, XRD analysis demonstrated that the majority of films were amorphous, with some polycrystalline and nanocrystalline samples. XRR data indicated a high roughness but did not yield good thickness values. Finally, XPS confirmed that material stoichiometry was preserved. It appears that the deposition process still needs optimization. This research will serve as the basis for future experiments on the magnetic properties of LSMO/BFO bilayers.

Influence of the Surface Roughness of Plasma-Sprayed YSZ on LSM Cathode Polarization in Solid Oxide Fuel Cells

Under SOFCs operating condition, the cathode reaction rate is determined by triple phase boundary (TPB) areas which are associated with the geometry of the interface between the cathode and the electrolyte. In this paper, YSZ electrolyte was deposited by atmospheric plasma spraying (APS). A nano-scaled lanthanum strontium manganate (LSM) cathode was prepared by sol-gel process on APS YSZ with different surface roughness to aim at increasing the TPB. The polarization curves of LSM cathode were characterized by potentiostat. The influence of the roughness of APS YSZ on the polarization of LSM cathode was investigated. It was found that the overpotential of the LSM cathode is significantly reduced with the increase of YSZ surface roughness.

Fatigue Properties of Lanthanum Strontium Manganate–lead Zirconate Titanate Epitaxial Thin Film Heterostructures Produced by a Chemical Solution Deposition Method

A liquid-precursor process was used to produce an epitaxial all-oxide ferroelectric memory device structure. The lanthanum strontium manganate–lead zirconate titanate–lanthanum strontium manganate (LSMO–PZT–LSMO) structure used for this device shows excellent polarization and fatigue behavior with a remnant polarization Pr of 42 µC/cm2 and a coercive field Ec of 68 keV. The polarization was found to only slightly degrade after over 1010 fatigue cycles. This behavior is contrasted with epitaxial PZT using a metal top electrode. In addition, the use of a top LSMO electrode was a sufficient barrier to Pb loss during heating to allow subsequent (or prolonged) heat treatments that would generally lead to Pb loss.