Search

PbZrO3 (PZO)/PbTiO3 (PTO) artificial superlattices have been grown on La0.5Sr0.5CoO3 (LSCO) (100)/MgO (100) substrate by pulsed laser deposition (PLD) with various stacking periods from 1 to 100 unit-cells. The ferroelectric properties of the superlattices were investigated by scanning probe microscopy (SPM). We have compared the superlattices to Pb(Zr0.5Ti0.5)O3 (PZT) thin films with respect to topographic features (roughness and grain size) and local polarization behavior. The polarization of PZT and superlattices was evaluated by measuring the surface potential using Kelvin force microscopy (KFM). The roughness and grain size of the superlattices were smaller than that of PZT thin films. The surface potential of superlattice with a 2 unit cell-stacking period (PZO2/PTO2) was as large as 1009 mV compared to PZT thin films with same thickness (i.e., 50 nm). As the total thickness of PZO2/PTO2 decreased, the corresponding surface potential decreased. The polarized domain size of the superlattice was depen...

SrMoO4 thin films were fabricated on Si (100) surface from half-metallic Sr2FeMoO6 target in oxygen atmosphere. Structural properties of SrMoO4/Si(100) thin films were investigated by x-ray diffraction and transmission electron microscopy. It was found that SrFeO3 − δ nanoclusters were dispersed in the SrMoO4 matrix, showing obvious M-H hysteresis loops.

We could systematically control the strain states of a Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} film by depositing a very thin Ba{sub 1{minus}x}Sr{sub x}TiO{sub 3} interlayer between the main layer of the Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} and a MgO(001) substrate. Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} films showed very strong dependence of dielectric properties on the strain states. The strain induced by the MgO substrate was relaxed faster than that induced by an interlayer.

Our work on tunable rf and microwave devices based on 90° off-axis magnetron sputtered Ba0.6Sr0.4TiO3 epitaxial thin films is reviewed. In particular, we have studied the effects of energetic bombardment during deposition on the structural and electrical properties of these films. The fundamental result of changing the energetic bombardment conditions during deposition is to affect the stress/strain state of the films. We show that high bombardment conditions result in films with significantly extended out-of-plane lattice constants and depressed dielectric constants and tunabilities.

(La,Sr)CoO3/Pb(Zr,Ti)O3/(La,Sr)CoO3 (LSCO) heterostructures have been grown on LaAlO3 substrates by pulsed laser deposition (PLD) to investigate asymmetric polarization switching of Pb(Zr,Ti)O3 (PZT) thin films with different electrode configuration. P-V hysteresis loop of LSCO/PZT/LSCO was symmetric. However, LaCoO3 (LCO)/PZT/LSCO showed a largely asymmetric P-V hysteresis loop and large relaxation of the remanent polarization at the negatively poled state, which means that the negatively poled state was unstable. On the other hand, LSCO/PZT/LCO exhibited large relaxation of the positively poled state. The asymmetric behavior of the polarized states implies the presence of an internal electric field inside the PZT layer. It is suggested that the internal electric field caused by built-in voltages at LCO/PZT and LSCO/PZT interfaces. The built-in voltages at LCO/PZT and LSCO/PZT interfaces were 0.6 eV and 2.1 eV, respectively.