bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy-Beam Processing Studies on Ta/U and Ir/Ta Systems
Authors: Kaufmann E. N. , Peercy P. S. , Jacobson D. C. , Draper C. W. , Huegel F. J. , Echer C. J. , Makowiecki D. M. , Balser J. D. 
Published: March 2011

ABSTRACTFilms of Ta metal on uranium and of Ir metal on tantalum have been irradiated and melted by pulses from Q-switched Ruby and frequency-doubled Nd:YAG lasers to investigate the nature of the resulting mixtures in light of the very different binary-phase diagrams of the two systems. In addition, a two-phase Ir-Ta alloy has been surface-processed with CW CO2 -laser radiation and with an electron beam in order to study microstructure refinement and test the advantage of using alloys as opposed to film-on-substrate combinations for the developement of claddings.
Fundamentals of Energy Beam Interactions with Solids
Authors: Brown W. L. 
Published: March 2011

ABSTRACTHigh intensity pulsed beams of photons, electrons and ions provide extremely efficient means for electronically exciting solids near their surfaces. Among these three, laser beams with ever-increasing time resolution have also served as diagnostic probes to clarify the picosecond time scale on which interchange of energy between the electronic and the vibrational states of solids takes place at very high excitation energy densities. Because of this rapid transfer of electronic excitation to heat, pulsed beams provide versatile tools to investigate transient thermodynamic phenomena in solids, particularly those associated with metastable phases such as amorphous silicon.
Multiplet Fine Structure of the Gd and Tb 5P Levels
Authors: Li Dongqi , Dowben P.A. , Onellion M. 
Published: March 2011

AbstractFine structure is observed in the photoemission of Gd and Tb 5p levels as a result of multiplet splitting. These splittings are the consequence of different J final states that occur as a result of interactions with partly filled 4f and/or 5d levels.
Structural and Magnetic X-RAY Scattering Measurements of Epitaxial Dy thin Films
Authors: Toney Michael F. , Wiesler David G. , Hermsmeier Brent D. , Farrow Robin F. 
Published: March 2011

AbstractWe report structural and magnetic X-ray scattering measurements of a 2000Å thick Dy film, sandwiched by LaF3 films on a GaAs(111) substrate. The structure was grow by molecular beam epitaxy with the c-axis of the Dy parallel to the LaF3 c-axis and GaAs[111] axis. For the magnetic X-ray scattering, we used a polarization analyzer and an X-ray energy near the Dy L111 absorption edge. ∆t this energy there is a resonant enhancement in the magnetic scattering intensity, and we obtained ≃-50 counts per second in the magnetic diffraction peaks.Between 85 and 179K, bulk Dy forms a helical antiferromagnetic structure, and below 85K, it transforms into a ferromagnet. We find that the c-axis lattice constant of the Dy film has a similar temperature dependence to bulk Dy from room temperature to about 110K, but below this, the film behaves differently from bulk and is strained. The temperature dependence of the turn-angle in the helical antiferromagnetic state is similar to bulk, although a weaker dependence is observed below ∼1 10K due to magnetoelastic effects. Surprisingly, the magnetic coherence length (≃310Å) is significantly shorter than the structural coherence length (≃730Å). The transition to ferromagnetic ordering at 86K exhibits temperature hysteresis as is evident in the structural and magnetic X-ray data and in SQUID magnetometry data. We believe this hysteresis arises from a combination of the strain-energy barrier accompanying the transition and magnetic inhomogeneities in the film.
Interlayer Magnetic Coupling in Sputtered Ag/Ni Superlattices
Authors: Dos Santos Carlos A. , Rodmacq Bernard 
Published: March 2011

AbstractWe report results of X-ray diffractometry and magnetic measurements performed on Ag/Ni superlattices prepared by triode dc-sputtering. The X-ray results suggest structural coherence and interface sharpness whatever the thickness of the elemental layers with (111) textures for both Ag and Ni. Magnetization measurements confirm the existence of sharp interfaces. They also indicate that the magnetic moments preferentially lie in the plane of the layers whatever the Ag or Ni thicknesses. We also present evidence of the oscillatory character of the magnetic coupling of the Ni layers through the non-magnetic Ag layers, which correlates with both magnetoresistance and low-angle neutron diffraction experiments.
Influence of Layer Structure on Antiferromagnetic Exchange Coupling of Iron Films through Chromium Interlayers
Authors: Payne A.P. , Kataoka H. , Farle M. , Clemens B.M. 
Published: March 2011

AbstractThe effect of layer structure perturbations on antiferromagnetic coupling in Fe-Cr-Fe trilayer systems is investigated. By varying the sputtering pressure, the layer structure of Fe-Cr-Fe trilayers is systematically altered, as indicated by changes in the low angle superlattice spectra of multilayers fabricated under identical conditions. The effect of topographic roughness is investigated by fabricating identical trilayers on Cr buffer layers of different thickness. Scanning tunneling microscopy is used to measure surface roughness. In each case the saturation field is measured as a function of Cr interlayer thickness by means of tapered Cr interlayer structures in which the thickness of the spacer varies linearly from 0 to 28 Å upon a single substrate. Antiferromagnetic coupling is measured locally by means of the magneto-optic Kerr effect. Results show that although the coupling is diminished by structural perturbations, it is a remarkably robust effect which persists even in instances of poor layer structure.
Magnetic Exchange Interaction Between Fe(110) Layers across a Ag(111) Intervening Layer
Authors: Qiu Z. Q. , Gutierrez C. J. , Tang H. , Mayer S. H. , Walker J. C. 
Published: March 2011

AbstractWe have grown a series of Fe(110)/Ag(111)/Fe(110) sandwich structures using a PHI 430B MBE system and analyzed their magnetic properties using transmission Mössbauer spectroscopy. The heterostructures consisted of two 30-monolayer (ML) 56Fe(110) slabs separated by an intervening Ag(111) layer 2 to 35 ML thick, with a 2 ML 57Fe Mössbauer probe layer placed at one of the Fe/Ag interfaces. We found that temperature dependence of the hyperfine field in the probe layer and the saturation hyperfine field value as well stronly depend on the Ag interlayer thickness. This result demonstrates that there exists an interlayer magnetic exchange interaction between the Fe layers across Ag. In addition, preliminary evidence suggests that this is probably an RKKY interaction.
Soft X-RAY Magnetic Scattering Study of thin Films and Multilayers
Authors: Kao C.-C. , Johnson E.D. , Hastings J.B. , Siddons D.P. , Vettier C. 
Published: March 2011

AbstractA brief discussion of the resonant magnetic scattering process is given. Results from recent studies of thin Fe films and Fe/Gd multilayers are used as examples to demonstrate the information can be obtained and the unique features of this technique: large resonant enhancement, sensitivity to magnitization, elemental specificity, and tunability of the penetration depth. Comparison is made with related techniques: magneto-optical Kerr effect, Faraday effect, and magnetic circular dichroism.
Ordering In Zn0.5Fe0.5Se Epilayers Grown on InP Substrates by Molecular Beam Epitaxy
Authors: Riba L. Salamanca , Park K. , Jonker B. T. 
Published: March 2011

AbstractWe have observed an ordered structure in Zn0.5Fe0.5Se epilayers grown on (001) InP substrates using transmission electron microscopy. The ordered structure of Zn0.5Fe0.5Se has Fe atoms occupying the (0,0,0) and (½, ½, 0) sites and Zn atoms occupying the (0, ½, ½) and (½, 0, ½) sites in the zinc-blende unit cell. Ordering is observed in both electron diffraction patterns and cross-sectional high-resolution lattice images along the < 100 > and < 110 > directions. This ordered structure consists of alternating ZnSe and FeSe monolayers along the < 100 > and < 110 > directions. Computer image simulations of the high-resolution images under various thicknesses, and defocusing conditions have been obtained and are compared with those obtained experimentally.
High-Pressure X-Ray Diffraction Studies of Elastic Anomalies in Superlattice
Authors: Fujii Y. , Ohishi Y. , Konishi H. , Nakayama N. , Shinjo T. 
Published: March 2011

AbstractThis paper has made an overview on elastic and structural aspects of three distinct superlattices under hydrostatic pressure up to about 8GPa, which were studied by our unique x-ray diffraction technique incorporated with a diamond-anvil cell. They are metallic fcc/fcc Au/Ni, bcc/fcc Mo/Ni, and semiconductive epitaxially-grown PbSe/SnSe superlattices. In their layer-stacking direction, both metallic superlattices show the supermodulus behavior while the semiconductive one doesn't. However, its pressure-driven cubic-to-orthorhombic phase transition, successively taking place in the SnSe and PbSe layers, has been found to significantly shift by stress due to its epitaxial growth.
Structural Properties of Epitaxial Co-Cr Superlattices
Authors: Elagoz S. , Vavra W. , Uher C. , Clarke Roy 
Published: March 2011

AbstractWe demonstrate the growth of epitaxially ordered Cobalt-Chromium (Co-Cr) superlattices by ultrahigh-vacuum deposition techniques. The superlattices, consisting of hcp Co (00.1) and hcp Cr (00.1) layers with their [11.0] crystallographic axes parallel to GaAs [110] have a hexagonal closed packed (hcp) structure with the c-axis normal to the film plane.
A Comparison of Growth and Magnetic Properties of FE(ll0)/AG(lll) and FE(100)/AG(100) Multilayers
Authors: Walker J.C. , Tang H. , Wieczorek M.D. , Keavney D.J. , Storm D.F. , Qiu Z.Q. , Gutierrez C.J. 
Published: March 2011

AbstractTwo series of Fe/Ag multilayers were grown in a Perkin-Elmer 430B MBE system, one of the Fe(110)/Ag(lll) orientation and another of the Fe(100)/Ag(100) orientation. Vastly different techniques were developed by this group and others to achieve epitaxial growth of both of these systems. Using RHEED, it was inferred that the optimal growth of Fe(110) on Ag(lll) occurred at a substrate temperature of 180° C. In contrast, the growth of Fe(lO0)/Ag(100) proceeded with the sharpest RHEED streaks at a reduced substrate temperature. We believe that these fundamentally different growth parameters are the result of physically different growth modes, conjectured to be: edge growth (Fe 110), and a more nucleated growth (Fe 100).Accordingly, dissimilar magnetic interfacial properties are also strongly in evidence, accounted for by the structural differences associated with the different Fe planes. Furthermore, Fe(110) layers as thin as 3 ML were grown on Ag(lll) and showed no superparamagnetism and a genuine 2-dimensional behavior of M(T). However, the Fe(100) on Ag(100) multilayers in a similar thickness range exhibited strong relaxation and a comparatively reduced Curie temperature.
Magnetic Anisotropy of Epitaxial Co/Pt Superlattices
Authors: Chien C.J. , Clemens B.M. , Hagstrom S.B. , Farrow R.F.C. , Lee C.H. , Marinero E.E. , Lin C.J. 
Published: March 2011

AbstractSelected orientations of epitaxial Co/Pt superlattices were grown on GaAs substrates in [001], [110], and [111] orientations using seeded epitaxy techniques. The microstructural and magnetic properties of Co/Pt superlattices are presented. The magnetic anisotropies of Co/Pt superlattices are found strongly dependent on the crystallographic orientation of the growth axis. High-resolution cross-sectional transmission electron microscopy (HRXTEM) investigation of the Co/Pt interfaces has revealed the presence of a large number of planar defects in the [111] Co/Pt superlattice. HRXTEM shows that the interface of Co/Pt is wavy and is not atomically abrupt. These findings suggest that models for the magnetic anisotropy should not be based on idealized, chemically abrupt interfaces but should incorporate magnetocrystalline anisotropy in the alloy region. We propose a model for the magnetic anisotropy based on the N6el magnetic surface anisotropy and the existence of defects in the alloy region. The easy axis of the magnetic anisotropy predicted by the model agrees with the magnetic and structural data for the superlattices.
Magnetic Anisotropy Determined from Angular Dependent Magnetization Measurements
Authors: Bloemen P.J.H. , Alphen E.A.M. Van , Jonge W.J.M. De , Broeder F.J.A. Den 
Published: March 2011

AbstractIt is shown that a (biaxial) vibrating sample magnetometer (VSM) can be used to determine the magnetic anisotropy of thin films. Besides the commonly measured component along the magnetic field also the component perpendicular to the magnetic field was measured. Experiments were performed in a magnetic field of fixed magnitude as a function of the angle between the field and the film plane. These type of measurements give both an accurate estimate of the magnetic anisotropy and also show when domains are formed during rotation of the magnetization. The method has been applied to determine the magnetic anisotropy of Co/Pd and Co/Cu multilayers. The results are compared to those obtained with alternative methods.
Magneto-Optical Enhancement of Tbfeco/Al Films at Short Wavelength
Authors: Song Kibong , Ito Hiroshi , Naoe Masahiko 
Published: March 2011

AbstractThe bilayered films composed of magneto-optical(MO) amorphous Tb-Fe-Co alloy and reflective Al layers were deposited successively on glass slide substrates without plasma exposure by using the facing targets sputtering system. The specimen films with the thickness of MO layer tMO below 5 nm showed apparent perpendicular magnetic anisotropy constant Ku of 2 to 3×106 erg/cm3 and rectangular Kerr loop. The specimen film with tMO of 14 nm took the Kerr rotation angle θk as large as about 0.36 degree, at the wavelength λ as short as about 400 nm. These values of θK is considerably larger than those of the bilayered films in the conventional MO media. Normally, the bilayered films with tMO above 50 nm took θK of about 0.25 degree at θK of 400 nm.
Spin Polarized Photoemission from Fe On CU(100)
Authors: Pappas D.P. , KÄmper K.-P. , Miller B.P. , Hopster H. , Fowler D.E. , Luntz A.C. , Brundle C.R. , Shen Z.-X. 
Published: March 2011

AbstractThe spin resolved electronic structure of ultra-thin Fe films on Cu(100) was investigated using spin polarized angle resolved photoemission spectroscopy. All exchange splitting of the Fe ∆s band of 2.5 eV is observed for photon energies between 20 and 30 eV. ∆ peak at 6 eV binding energy which has been previously identified as a many-electron resonance was observed only after contamination of the films with oxygen. In addition, the spin dependent attenuation lengths for electrons in Fe were measured at 11, 19, and 40 eV above Ef. The attenuation length for the minority spin electrons was found to be shorter than that of the majority spin electrons. The difference between the two attenuation lengths was shown to increase at low energy. Short attenuation lengths of ≃3 monolayer were measured at II eV. The large increase of the attenuation length at low energy which is expected from the “universal curve” is not observed in Fe.
Spin Polarization of PT in Pt/Co Multilayers Studied by X-Ray Absorption
Authors: Schütz G. , Ebert H. , Fischer P. , Rüegg S. , Zeper W. B. 
Published: March 2011

AbstractLocal d-magnetic moments of the Pt interlayer in Pt/Co multilayered structures (4 ÅCo + X ÅPt, X=9,19,23,30,40) have been investigated theoretically and experimentally by circular magnetic x-ray dichroism studies.It has been found that a significant Pt polarization is induced, which contributes by about 13% to the total magnetization. The experimental findings of the average Pt moments agree well with the theoretical expectations indicating the existence of a longrange exchange coupling through the Pt layer.
Doping And Band-Gap Engineering Of An Intrazeolite Tungsten(Vi) Oxide Supralatiice
Authors: Ozin Geoffrey A. , Malek Andrzej , Prokopowicz Richard , Macdonald Peter M. , özkarb Saim , Mollerc Karin , Bein. Thomas 
Published: March 2011

ABSTRACTNew results are presented concerning the topotactic self-assembly, n-type doping and band-gap engineering of an intrazeolite tungsten(VI) oxide supralattice n(WO3)-Na56Y, where O < n ≤ 32, built-up of single size and shape (WO3)2 dimers. In particular it has been found that the oxygen content of these dimers can be quantitatively adjusted by means of a thermal vacuum induced reversible reductive-elimination oxidative-addition of dioxygen. This provides access to new n(WO3−x)−Na56Y materials (0 < x ≤ 1.0) in which the oxygen content, structural properties and electronic architecture of the dimers are changed. In this way one can precisely control the oxidation state, degree of n-doping and band-filling of a tungsten(VI) oxide supralattice through an approach which can be considered akin to, but distinct in detail to, that found in the Magneli crystallographic shear phases of non-stoichiometric bulk WO3−x. Another discovery concerns the ability to alter local electrostatic fields experienced by the tungsten(VI) oxide moieties housed in the 13Å supercages of 16(WO3)−M56Y, by varying the ionic potential of the constituent supercage M+ cations across the alkali metal series. This method provides the first opportunity to fine-tune the band-gap of a tungsten(VI) oxide supralattice. A miniband electronic description is advanced as a qualitative first attempt to understand the origin of the above effects. The implications of these discoveries are that cluster size, composition and intrinsic electrostatic field effects can be used to “chemically manipulate” (engineer) the doping and band architecture of intrazeolite supralattices of possible interest in quantum electronics and nonlinear optics.
Growth, size and photoactivity of CdS, ZnS or PbS particles in NaX zeolite
Authors: Wark M. , Schulz-Ekloff G. , Jaeger N. I. , Lutz W. 
Published: March 2011

ABSTRACTCdS, ZnS or PbS dispersions are prepared in a NaX matrix by ion exchange and gas phase sulfidation. The degree of sulfidation remains incomplete in all cases. This fact can be explained by preferential bonding of the cations to the zeolite framework and to an increase of the solubility constants for quantum-size particles. Zeolite-hosted sulfide particles grow to supra-supercage size under fragmentation of the host framework. The shift of the position of the optical absorption edge correlates with the sulfide particle size obtained from transmission electron micrographs. The rate of photocorrosion of the sulfide clusters strongly depends on the particle size between 1 and 10 nm.
Zeolitic Materials As Organizing Media For Semiconductor-Based Artificial Photosynthetic Systems
Authors: Il Kim Yeong , Riley Richard L. , Huq Munir J. , Salim Samer , Le Angie N. , Mallouk Thomas E. 
Published: March 2011

ABSTRACTTwo photocatalytic systems consisting of spatially organized electron donor/photosensitizer/oxide semiconductor/catalyst assemblies are described. The first consists of an aluminosilicate zeolite (mordenite or zeolite L) containing Pt clusters, methylviologen, and titanium oxide within the linear channels, together with a size-excluded photosensitizer RuL32+ (L = 4, 4-dicarboxy-2, 2-bipyridine) adsorbed at the TiO2 surface. The kinetics of photochemical charge separation and hydrogen evolution in the presence of sacrificial electron donors are reported. In the second system, a layered oxide semiconductor, K4−xHxNb6O17·nH2O, replaces the zeolite/TiO2/MV2+ composite. Using adsorbed RuL3 and visible light excitation, this material decomposes acidic iodide solutions into H2 and I3− with a quantum efficiency of 0.3 %.
Surface Chemistry Of Heterobimetallic Ge-M (M = Mo, W) Complexes In Zeolite Y
Authors: Borvornwattananont Aticha , Moller Karin , Bein Thomas 
Published: March 2011

ABSTRACTThe intrazeolite chemistry of the two germylene complexes Cl2(THF)GeM(CO)5(M = Mo, W) was studied with x-ray absorption spectroscopy (Ge, Mo, W edge EXAFS) and in-situ FTIR/TPD-MS techniques. The slightly decarbonylated GeMo complex interacts with the framework of NaY zeolite at room temperature and retains the Ge-Mo bond up to about 100° C. In proton-loaded HY zeolite, framework interactions increase at elevated temperature, and the attached complex retains the Ge-Mo bond up to about 120° C. The Ge-Mo bond is cleaved at higher temperatures. MoC1x and Mo-Mo species are formed in NaY and HY zeolite, respectively, while GeClx fragments are anchored to the zeolite framework.The complex Cl2 (THF)GeW(CO) 5 retains all five CO ligands up to about 100° C in both NaY and the proton form. Detectable anchoring occurs at room temperature in NaY and at about 80° C in the proton form. WC1x species are formed upon cleavage of the Ge-W bond at higher temperatures.
The Application Of Molecular Sieves As Magnetic Resonance Imaging Contrast Agents
Authors: Balkus Kenneth J. , Bresinska Iwona , Kowalak Stanislaw , Young Stuart W. 
Published: March 2011

ABSTRACTThe application of zeolite molecular sieves as Magnetic Resonance Imaging (MRI) contrast agents is presented. Recent progress is described for X, Y and A type zeolites modified with paramagnetic species.
Synthesis And Water Sorption Properties Of Aluminophosphate (AlPO4) And Silicoaluminophosphate (Sapo) Molecular Sieves
Authors: Malla P. B. , Komarneni S. 
Published: March 2011

ABSTRACTAluminophosphate (AlPO4–5, AlPO4–11, AlPO4–17, AlPO4–20) and silicoaluminophosphate (SAPO-5, SAPO- 11, SAPO-17, SAPO-20) molecular sieves of varying pore sizes (3–8 Å) were synthesized and their water adsorption and desorption properties were studied. Water sorption isotherms of AlPO4 molecular sieves were characterized by unusual isotherm shapes, that is, little or no initial adsorption followed by extreme adsorption leading to volume filling by hydrogen bonding and cooperative interaction in micropores, apparently due to the nonpolar nature of pore surfaces coupled with weak (reversible upon evacuation) chemisorption of water, and hysteresis loops extending to very low pressures. Although micropore filling in AlPO2's and isostructural SAPO's was completed almost at the same relative pressure (p/po), SAPO's exhibited less extreme adsorption isotherms as a result of their slightly more polar nature of pore surfaces compared to AlPO4's. Neither AlPO4apos;s nor SAPO's exhibited Brunauer Type I isotherms with water, contrary to a general expectation of the hydrophilic microporous solids.
The Hydrothermal Synthesis of Layered Molybdenum Phosphates with Octahedral-Tetrahedral Layers
Authors: Haushalter Robert C. , Mundi Linda A. 
Published: March 2011

ABSTRACTWhile we have prepared and structurally characterized over forty solids in the octahedral-tetrahedral framework molybdenum phosphate (MoPO) system, including molecules, 1-D polymers and 3-D materials, this paper will focus on the two dimensional layered MoPO's. Both covalently and H bonded layers will be discussed. Compounds covered include Na3[Mo2O4(HPO4)(PO4)]·2H2O, (Et2NH2)2[Mo4O8(PO4)4/2], Cs2Mo4P6O26, (4-phenylpyridie)2[Mo4O8(PO4)4/2], (cation)[Mo2O2(PO4)2(H2PO4)], with several different types of organic and inorganic cations, and (4-phenylpiperidine)4[Na2.5Mo6O15(H1.4PO4)4]·4H2O. These materials might provide a platform for the preparation of new types of pillared and intercalated inorganic solids.