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High-resolution 3-Dimensional Reciprocal Space Mapping (3D-RSM) has been performed on mixed-phase BiFeO3 (BFO) epitaxial films on (001)-oriented LaAlO3 substrates. Our results demonstrate that 3D-RSM is an effective way to present a structural overview of the different BFO polymorphs, domain variants, and even the interfacial regions between coexisting triclinic phases. The dislocation-free boundaries between the triclinic phases revealed by these 3D-RSMs are believed to be responsible for the large electromechanical response found in mixed-phase BFO films. This study demonstrates the unique merits of the 3D-RSM technique for the structural characterization of ferroic films with complicated domain structures. [ABSTRACT FROM AUTHOR]

Multiferroic (001)-Zn0.4Fe2.6O4/0.7Pb(Mg2/3Nb1/3)O3-0.3PbTiO3 (ZFO/PMN-PT) epitaxial heterostructures have been investigated to demonstrate the electric-field-controlled resistance and magnetization switching. The tunabilitiy of resistance of the ZFO film is about -0.1% under the in-plane strain -0.02% at 296 K and 0.2% for the electric field 1.0 kV/cm at 80 K, respectively, and the tunabilitiy of magnetization is about 1.1% under the in-plane strain -0.11% at 296 K, which is attributed to the controllable strain transferred into the ZFO film from the piezoelectric PMN-PT substrate. A possible microscopic mechanism of the manipulation of resistance and magnetization is the enhancement of hopping amplitude of electrons between mixed-valent Fe2+ and Fe3+ ions under the electric-field-induced in-plane compressive strain. [ABSTRACT FROM AUTHOR]

Heterojunctions composed of La0.7Ca0.3MnO3 and 0.05 wt % Nb-doped SrTiO3 were fabricated using pulse laser deposition. The current-voltage characteristics of such heterojunctions can be described by tunneling with an effective Schottky barrier. These junctions showed significant response to ultraviolet and visible light. Band-to-band and internal photoemission were characterized by photoelectric experiments. A quantum efficiency of about 86% was observed at an incident energy of ∼3.95 eV, which corresponds to the band-to-band excitation of electrons in Nb:SrTiO3. From the internal photoemission, the height of Schottky barrier was determined as 1.64 eV. [ABSTRACT FROM AUTHOR]

Introducing oxygen vacancy causes the dielectric insulator SrTiO3 to evolve to a n-type semiconductor. The authors have fabricated n-SrTiO3-δ(110)/p-Si (100) heterojunctions, showing clear rectifying characteristics at different temperatures from 100 to 292 K. A forward-to-reverse bias ratio of about 1200 was found at V=±2 V for the p-n junction operated at T=292 K. The current-voltage characteristic follows I∝exp(eV/ηkT) for the p-n junction at relatively low forward-bias voltage, while the relation of I∼V1.9 describes the transport behavior of p-n junction at relatively high forward-bias voltage. The measured results have been discussed in Anderson model and space charge limited model. [ABSTRACT FROM AUTHOR]

An efficient and high output power laser has been realized for an Er:Yb:YAl3(BO3)4 crystal end pumped by a 970 nm diode laser. Under the absorbed pump power of 15.5 W, quasi-continuous-wave output power of 2.0 W at 1.5–1.6 μm has been obtained in a hemispherical cavity. The laser had an absorbed pump threshold power of 4.7 W and a slope efficiency of 21%. The influence of the laser output power and output coupler transmission on the output laser spectra has also been investigated. [ABSTRACT FROM AUTHOR]

We present an investigation in NdAl[sub 3](BO[sub 3])[sub 4] (NAB) crystal of the excited-state absorption (ESA) around the main laser lines (1060 and 1338 nm) by the so called excited-state excitation technique. The involved transitions are from the [sup 4]F[sub 3/2] level toward the [sup 4]G[sub 7/2]+[sup 4]G[sub 9/2]+[sup 2]K[sub 13/2] levels (1300–1400 nm range) or toward the [sup 2]G[sub 9/2]+[sup 4]G[sub 11/2]+[sup 2]D[sub 3/2]+[sup 2]K[sub 15/2] levels (1020–1100 nm range). We have performed the Judd–Ofelt analysis extended to anisotropic crystals in order to get the cross sections (cm[sup 2]). In each case, the ESA peaks do not coincide with the laser emission ones, but a reduction of the effective laser emission cross section is observed at 1338 nm. Finally, the values obtained from the application of the Judd–Ofelt formalism have been used to estimate the influence of ESA in the pumping domain on the laser performance. It has been found that its contribution is not significant, indicating that NAB is an excellent candidate for efficient high-power microchip lasers emitting at 1060 and 1338 nm. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This letter reports our study of the temperature dependence of gate currents in thin Ta[sub 2]O[sub 5] and TiO[sub 2] films. The study was conducted (1) to study the conduction mechanisms and band alignments, and (2) to determine whether the gate leakage current is tolerable at high temperatures for either of these high-dielectric-constant (high-k) oxides. The I–V characteristics of these oxides were measured and analyzed over a wide temperature range from 25 to 400 °C. Currents in Ta[sub 2]O[sub 5] samples exhibited stronger temperature dependence than those in TiO[sub 2] samples, especially at high fields, mainly due to a much smaller electron barrier height of Ta[sub 2]O[sub 5] over Si (0.28 eV) than that of TiO[sub 2] over Si (0.9 eV). © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Extrinsic contributions play an important role in the functionalities of ferroelectric materials, while domain structure evolution is crucial for understanding the extrinsic dielectric and piezoelectric responses. In this work, domain configuration changes with an electric field applied along [001] C in the tetragonal (K, Na, Li)(Nb, Sb, Ta)O 3 single crystal were studied by means of polarizing light microscopy. Results show that parts of the spontaneous polarizations in the (001) C plane are switched to [001] C direction, while others still stay in the (001) C plane due to high induced internal stresses. Single domain state cannot be achieved even under a high electric field. After being poled along [001] C , the volume fraction of domains with polarzations in the (001) C plane is still about 25.2%. The extrinsic contributions to the dielectric constant are 15.7% and 27.2% under the E field of 1 kV/cm and under 2 kV/cm, respectively, estimated by the Rayleigh analysis.