bluuebunny/crossref_metadata_2025_split huggingface dataset:
MBE-Growth of Iron and Iron Oxide Thin Films on MgO(1OO), Using NO2, NO, and N2O as Oxidising Agents
Authors: Voogt F. C. , Hibma T. , Smulders P.J.M. , Iesen L. , Fujii T. 
Published: April 2011

ABSTRACTWe have made a study of the use of NO2 as the source of oxygen in the MBE-growth of iron oxides thin films. It is found that NO2 is a much more efficient oxidising agent than molecular O2. As indicated by Mössbauer spectroscopy, performed on 57Fe probe layers, NO2 is not only capable of forming stoichiometric magnetite Fe3O41 but also all non-stoichiometric Fe3-δO4 phases. Even the metastable maghemite phase γ-Fe2O3 (Fe3-δO4 with δ=1/3) can be formed. All iron oxides grow layer-by-layer-like, as indicated by strong RHEED intensity oscillations. When small doses of NO2 are used, new wustite Fe3-xO and Fe3O4 phases are formed. In contrast to the Fe3-δO4 films, these phases have nitrogen incorporated into the crystal lattice. Similar compounds are obtained when NO is used as the source of oxygen. The use of N2O does not lead to the formation of iron oxides. It does, however, alter the growth mode of Fe on MgO(100). Whereas Fe deposited under UHV conditions forms 3D islands, the N2O acts as a surfactant and induces 2D layer-by-layer growth.
Characterization of Off-Axis Sputtered La0.67Ca0.33MnO3 Films and La0.67Ca0.33MnO3/YBa2Cu3O7-δ Bilayers
Authors: Broussard P. R. , Cestone V. C. , Qadri S. B. 
Published: April 2011

ABSTRACTThin films of the colossal magnetoresistive material La0.67Ca0.33MnO3 (LCMO) have been grown by off-axis sputtering from a single target of the LCMO material onto various substrates and studied by electrical transport, x-ray diffraction, scanning electron microscopy and atomic force microscopy. The LCMO films typically grow with the (002) direction oriented normal to the film. We find magnetoresistances at 6 T of ≈ 90%. We observe a scaling between the temperature of the resistivity peak (Tp) and the relative change in resistivity between room temperature and the resistance peak for Tp varying from 90 to 270 K. This scaling is consistent with an activated resistivity above the peak, with an activation temperature of ≈ 940 K. Films of LCMO grown on cubic zirconia exhibit an upturn in resistivity at low temperatures. Bilayers of LCMO and the superconductor YBa2Cu3O7-δ have been grown and compared to see the effects of having either the magnetic or superconducting layer first in the sequence.
Magnetoresisnve La-Sr-Mn-O Powders and Films by Daas Technique
Authors: Yang S. , Lin C.-T. , Rogacki K. , Dabrowski B. M. , Adams P. M. , Speckman D. M. 
Published: April 2011

ABSTRACTMagnetic perovskites of the general form La1-xSrxMnO3 have successfully been synthesized using deposition by aqueous acetate solution (DAAS). This novel technique, which has the potential for depositing large area min films with high throughput and low cost, involves the preparation of an aqueous metal acetate precursor solution, drying the solution to generate a glassy gel, consolidating the gel, and then firing it for short periods of time (<2hrs) to produce crystalline lanthanum strontium manganate (LSMO). The DAAS method has been used to prepare both powders and thin films of LSMO. Powder samples of La0.83Sr0.17MnO3 annealed for 100 minutes at 1200°C were high purity, single phase, and exhibited excellent electrical and magnetic characteristics. Thin films of La0.7Sr0.17MnO3 deposited onto both sapphire and strontium titanate substrates and annealed at 900°C were also found to be crystalline, and substrate choice was found to influence thin film crystal structure. These films exhibited sharp metal-insulator transitions, and in the case of LSMO films on strontium titanate, magnetoresistance was observed at the unusually high temperature of ∼360K.
High Quality Epitaxial V2O3 Thin Films: A Material for Infrared Switching Devices?
Authors: Schuler H. , Grigoriev S. , Horn S. 
Published: April 2011

ABSTRACTThe compound V20O13 undergoes a metal-insulator-transition (MIT) at T=150K with an optical gap in the insulating phase of ∼0.6eV. Therefore epitaxial films of V2O3 are of interest for infrared (IR) applications. We present the results of a systematic study of the growth conditions of such films utilizing electronic transport and infrared transmission measurements in addition to studies of crystal and microstructure.Epitaxial V2O3 thin films were grown in a reactive oxygen atmosphere on c-axis oriented sapphire substrates by electron beam evaporation. While V2O3 single crystals show a MIT in a narrow temperature range ΔT < 1K, the MIT broadened in epitaxial thin films due to defects and stress induced by the film-substrate interaction.In our study we defined the quality of the films by the width ΔT of the transition and the change of resistivity p and IR transmission at the MIT. We found the most important growth parameter to be the growth temperature. Only in a narrow region around 600°C the growth of high quality films was observed. The optical constants of such films were determined from IR transmission measurements in combination with an oscillator fit method. While the spectra in both the metallic and the insulting phase are dominated by d-d-transitions for photon energies above leV, in the IR region (λ > 2μm) a high transmission contrast between the two phases was almost independent of the wavelength. This behavior suggests e.g. applications as a non mechanical IR shutter or as switchable interference filter in the IR regime.
Origin of the (110) Orientation of Y2O3 and CeO2 Epitaxial Films Grown on (100) Silicon
Authors: Goettler R. L. , Maria J. P. , Schlom D. G. 
Published: April 2011

ABSTRACTA perplexing issue in the growth of epitaxial oxide films on (100) silicon is the observed (110) orientation of yttria (Y2O3) and ceria (CeO2) despite the (100) orientation having a lower lattice mismatch. As expected, yttria-stabilized zirconia (YSZ) grows with the (100) orientation, yet it has a worse lattice match than both Y2O3(100) and CeO2(100) with silicon (100). The orientations observed would be expected if an epitaxial metal suicide layer forms initially during growth, before the oxidizing ambient is introduced. Calculation of the ensuing lattice mismatch between the oxide and suicide layer and multiplicity (σoxide) of the near coincident-site lattice for the oxide lattice shows that the (110) orientation is better lattice-matched than the (100) orientation for both Y2O3 (+2.3% × -2.4%, σoxide= 2, vs. -2.4% × +3.5%, σoxide = 4) and CeO2 (+1.8% × -4.0%, σoxide = 5, vs. 1.9% × 1.9%, σoxide= 5) and that for YSZ, (100) is better lattice matched than (110) (-0.8% × -1.6%, σoxide = 1, vs. -1.1 % × +4.8%, σoxide = 3). In each case, the in-plane orientation yielding the lowest mismatch with the suicide layer is consistent with the in-plane orientation observed between the oxide film and silicon substrate. Furthermore, the commonly observed rotational twinning in the oxide film can be accounted for by the expected orthogonal domain multipositioning in both the suicide and oxide layers. In CeO2, multipositioning allows two equally matched sets of orthogonal domains. One set consists of the two experimentally observed orientations (related by a 90° rotation). The other set is rotated 37° from the commonly observed orientations. Only the set with orientations aligned to the surface steps of Si(100) is observed, indicating the likely influence of graphoepitaxy in selecting between the two degenerate sets of orientations. When grown on Pt(100), Y2O3 grows with predominantly the (100) orientation and no (110) orientation, suggesting that without suicide formation, Y2O3 will grow with the expected well matched (100) orientation even when polar interfaces are involved.
Epitaxial CeO2 on Silicon Substrates and the Potential of Si/CeO2/Si for SOI Structures
Authors: Morshed A. H. , Liu S. X. , Leonard R. , Mcintosh F. G. , El-Masry N. A. , Bedair S. M. 
Published: April 2011

ABSTRACTCeO2 is nearly lattice matched to Si and has the CaF2 cubic structure thus it offers the potential for the epitaxial growth of an insulating film on Si. Laser ablation of a CeO2 target in an ultra high vacuum system was used for the deposition of single crystal CeO2. The effect of post growth thermal and rapid thermal annealing in O2, N2 and Ar atmosphere was found to have pronounced effects on the electrical properties measured by C-V and the optical properties measured by photoluminescence.We report on our initial results for the growth of epitaxial Si on the deposited CeO2 using low pressure CVD. Both RHEED and TEM studies showed that single crystal epitaxial Si was deposited on CeO2. The details of the Si deposition on CeO2 films for potential of SOI (silicon on insulator) structures will be discussed.
Intrinsic Point Defects on a TiO2(110) Surface and Their Reaction with Oxygen: A Scanning Tunneling Microscopy Study
Authors: Kuhn Markus , Anderson J. F. , Lehman Jeremy , Mahmoud Talib , Diebold Ulrike 
Published: April 2011

ABSTRACTThe interaction of molecular oxygen, at room temperature, with a reduced TiO2(110) surface has been studied in situ by scanning tunneling microscopy (STM). Oxygen vacancies (point defects) were created on a clean TiO2(110) surface by annealing in ultra-high vacuum and successfully imaged on the atomic scale. These point defect sites were stable under ultrahigh vacuum conditions. During exposure to molecular oxygen, new point defects appear at different locations on the surface although their overall number is reduced. A mechanism for this dynamic healing process is proposed.
Epitaxial Growth And Optical Properties of Sol-Gel (Pb,La)Ti03 Thin Films for Waveguides
Authors: Koo Junmo , Lee Changho , No Kwangsoo , Bae Byeong-Soo 
Published: April 2011

ABSTRACTLead lanthanum titanate thin films have been prepared on MgO and sapphire substrates by sol-gel method. XRD analyses confirm that the PLT films fabricated on MgO(lOO) and c-plane sapphire substrates grow preferentially with (100) and (111) orientations, respectively. The PLT films with a high La content have a low refractive index due to the decrease of the refractive index anisotropy. The propagation losses in PLT films measured, using He-Ne laser light and the prism coupling method decrease as the La content increases. This is due to the reduction of the refractive index anisotropy and the surface scattering by the surface roughness as a function of La content in the film.
Microstructural Development Of thin CoCrTa Films on Cr Underlayers
Authors: Ross C.A. , Ross F.M. 
Published: April 2011

ABSTRACTThe structure of 2.8 – 60nm thick films of CoCrTa sputtered onto a 50nm Cr underlayer at 250°C was studied using atomic resolution microscopy. The Cr grows with a (200) orientation and the CoCrTa grows epitaxially with the [0002] axis in the film plane. The thinnest films have a discontinuous microstructure with several CoCrTa nuclei forming on each Cr grain, with slight misalignment from the exact Pitsch-Schrader orientation relation. The CoCrTa grains coalesce as the film thickness exceeds lOnm and there is evidence for stacking faults at all film thicknesses. For most films the magnetic switching volumes are of similar size to the physical grain volume, suggesting that the entire grain volume participates in magnetic switching.
Unusual Magnetic Behaviour of BCT Fe Thin Films Evidenced by 57Fe Mössbauer Spectrometry
Authors: Andrieu S. , Bauer Ph. , Lemine O. M. , Snoeck E. , Piecuch M. 
Published: April 2011

ABSTRACTUnusual magnetic behaviours occur in thin Fe films grown on Ir(100) by Molecular Beam Epitaxy. Four different magnetic sites are actually observed in these layers by Conversion Electron Mössbauer Spectrometry. The magnetic relaxation phenomena found in the strained FCC structure together with spin wave softening observed in the strained BCC structure point to small magnetic correlations along the growth direction.
Magnetic Anisotropy in Single Crystal Terfenol-D Thin Films
Authors: Oderno V. , Dufour C. , Dumesnil K. , Mougin A. , Bauer Ph. , Mangin Ph. , Marchal G. , Patrat G. 
Published: April 2011

ABSTRACTTb03.Dy0.7Fe2 (known as Terfenol-D) thin films have been epitaxially grown for the first time with [110] as the growth direction. X-Ray diffraction measurements evidence that the films are strained compared to the bulk alloy. Mössbauer spectroscopy and Kerr rotation measurements show that the easy magnetization direction varies from <116> at 4.2 K to around <133> at 300 K. This variation is different from the bulk case (for which the magnetization is along <100> at 4.2 K and along <111> at room temperature). This effect can be qualitatively understood if we consider the influence of the strains induced by epitaxy on the various energy terms which govern the direction of magnetization.
Step-Induced Magnetic Defects in Fe/Cr Systems
Authors: Freyss M. , Stoeffler D. , Dreysse H. 
Published: April 2011

ABSTRACTWe present the results of calculations of the magnetic order in Fe/Cr systems with a mono-atomic step at the interface. The study of such a systems is of particular interest since it is believed that topological defects play an essential role in the exchange coupling mechanism in Fe/Cr multilayered systems. We show that assuming only collinear magnetism, an interfacial step creates a very extended magnetic defect in the Cr layer. On the other hand, when the local magnetic moments are allowed to rotate, the magnetic defect is very localized near the step and the presence of the step induces a non-collinear coupling between the Fe layers in Fe/Cr superlattices.
Magnetic anisotropy of Fe/Cu(100) over- and interlayers
Authors: Újfalussy B. , Szunyogh L. , Weinberger P. 
Published: April 2011

ABSTRACTThe perpendicular magnetic anisotropy in Fe/Cu thin film over- and interlayers is investigated in terms of the fully relativistic spin-polarized band theory. The formation of the ground state is addressed and a layer-resolved analysis of the magnetic anisotropy energies for the Fe/Cu(100) and the Cu/Fe/Cu(100) system is presented both for ferromagnetic and anti-ferromagnetic cases.
Domain Topology of Micron-Scale, Ferromagnetic Pancakes
Authors: Bedrossian Peter J. , Gibbons Matthew R. , Cerjan Charles J. 
Published: April 2011

ABSTRACTPlanar, micron-scale ellipses patterned from 700Å-thick Co films exhibit nearly-complete suppression of hysteresis when magnetized in-plane along their short axes. Using a combination of Magnetic Force Microscopy and Vibrating Sample Magnetometry, we find that the suppression of hysteresis is associated with the continuous deformation of a dipole field configuration. The presence of hysteresis for in-plane, long-axis magnetization is associated with transitions between topologically inequivalent configurations.
Magnetic Properties of Multilayered Co-Cu Granular Composites
Authors: Cabbibo A. , Caballero J.A. , Park Y.D. , Childress J.R. 
Published: April 2011

ABSTRACTThe magnetic properties of granular CO25Cu75/CU multilayer films prepared by sputtering onto heated glass substrates have been investigated in the range of ultrathin alloy films (5–250Á) and Cu spacer thicknesses (0–50Å). Both the coercive field at 10K and the maximum superparamagnetic blocking temperature TB are found to be sensitive to finite-size effects in single-layer films, and to interactions between layers in multilayer films. Our results indicate that the magnetic properties of granular alloy layers can be engineered to a large extent by selectively modifying the local environment of the Co particles.
Residual Stresses in Ultrathin Metal Sublayers Within Au/Ni Multilayers
Authors: Labat S. , Gergaud P. , Thomas O. , Gilles B. , Marty A. , Lefebvre S. 
Published: April 2011

ABSTRACTMetallic Multilayers (MLs) have attracted a considerable interest during these last years because of their unusual properties. In small periods ML's (a few nm) the high density of interfaces give rise to structures very far from equilibrium. Au/Ni multilayers have been grown in the (111) orientation by M.B.E. on Si(100) via a Cu(100) buffer layer. Two different parameters have been studied: the Au:Ni ratio at constant (4 nm) superperiod and the superperiod at constant (1:1) Au:Ni ratio. The full strain state of Au and of Ni has been determined via x-ray diffraction measurements. The high lattice parameter misfit beween Au and Ni (14%) implies that all the layers are partially relaxed. Residual strains as high as several % are encountered. The residual strain in the Au layers is clearly correlated with their thickness. A residual stress as high as 3.9 GPa is determined in the thinner layers.
Magnetization on Vicinal Ferromagnetic Surfaces
Authors: Zhao D. , Liu Feng , Huber D.L. , Lagally M.G. 
Published: April 2011

ABSTRACTUsing Ising model Monte Carlo simulations, we show a strong dependence of surface magnetization on surface miscut angle. For ferromagnetic surfaces, when surface spin exchange coupling is larger than that of the bulk, the surface magnetic ordering temperature decreases, toward the bulk Curie temperature, with increasing miscut angle; when surface spin exchange coupling is smaller than that of the bulk, a crossover behavior occurs: at low temperature, the surface magnetization decreases with increasing miscut angle; at high temperature, the reverse is true.
Anomalous Behavior in Spin Dependent Tunnel Junctions
Authors: Platt C. L. , Dieny B. , Berkowitz A.E. 
Published: April 2011

ABSTRACTSpin dependent tunneling has been investigated in tunnel junctions composed of a variety of materials. The best results thus far have been with either HfO2 or MgO as the barrier layer using CoFe, Fe, or Co as the magnetic electrodes. The maximum magnetoresistive (MR) response of these junctions has been at low temperatures on the order of 30% in HfO2 and 20% in MgO. We have also observed a variety of anomalous behavior in some of our tunnel junctions at low temperature. These include MR effects dependent on the angle of orientation of the tunnel junction in the applied magnetic field, transition fields greater than lOkOe, and negative MR effects on the order of 2%.
Noncollinear Phase of Magnetic Multilayers
Authors: Morosov A. I. , Sigov A. S. 
Published: April 2011

ABSTRACTThere is considered the dependence of magnetic ordering type in multilayer structures on the magnitude of exchange interaction between magnetic layers and the interlayer surfaces roughness. With a simple example of the three-layered structure we found the areas of the existence of such states as: (i) domain structure, (ii) noncollinear ordering of homogeneous magnetic layers, (iii) collinear ferromagnetic phase, and (iiii) collinear antiferromagnetic phase.
Magnetic Field Sensors for Magnetic Position Sensing in Automotive Applications
Authors: Heremans Joseph P. 
Published: April 2011

ABSTRACTMagnetic position sensors are transducers whose output is an electrical signal that is a function of a mechanical motion. They consist of a permanent magnet, a magnetic field sensor, and a moving magnetic circuit. Being contactless, they do not wear out. Unlike optical systems, they are impervious to contamination. With the proliferation of microprocessor control in many on-board automotive applications, magnetic position sensing becomes a crucial function, found e.g. in cam and crankshaft sensors used for ignition timing and engine misfire detection, in brushless electrical motors, in wheel speed sensors and in other applications.This paper first reviews the requirements put on the magnetic field sensors in these applications. Five main types of field sensors are used: Si Hall sensors with integrated amplifiers, GaAs Hall sensors, InSb-based magnetoresistors, anisotropie magnetoresistors (AMR), and metal-multilayer magnetoresistors (GMR). Magnetoresistors are almost always used as differential pairs, either in Wheatstone bridges or with matched constant current sources. The two characteristics of each type of field sensors that matter most are their sensitivity to magnetic field, and the smallest amount of field modulation they can detect, i.e. their resolution, which is mainly limited by the drift of the outputs with temperature. These parameters are measured and reported here on the 5 types of sensors; the work is an update of a 1993 review by the author.
Giant Hall Effect and Spin-Dependent Transport in Granular NiFe-SiO2 Films
Authors: Yan X. , Pakhomov A. B. , Jing X. N. , Wong S. K. 
Published: April 2011

ABSTRACTIn granular NiFe-SiO2 films which display giant Hall effect, extraordinary Hall resistivity ρxys, normal Hall resistivity ρxyo, and magnetoresistivity δρ, were all found to follow power lav dependencies on resistivity ρ. Namely, -ρxys ∼ ρ0.81, -ρxyo ∼ ρ0.64 and -δρ ∼ ρ1.15. We propose that the presence of nanometer sized particles in the percolating conduction channels gives rise to I giant enhancement for both ordinary and extraordinary Hall effect in magnetic metal-insulator nanocomposite films. This physical picture describes qualitatively well the general features of GHE, and its correlation with resistivity and magnetoresistivity.
Influence of Dielectric Film Thickness on the Magnetic Properties of the Magneto-Optical Multilayer Films
Authors: Miao X.S. , Chan Y.C. , Huang Y.M. , Liu W.Z. , Lee Z.Y. 
Published: April 2011

ABSTRACTThe magnetic interaction of magneto-optical multilayer films have been analyzed using the stress mechanism of coercivity and the single ion model of magnetic anisotropy. The relation between the magnetic properties of the multilayer films and the dielectric film thickness has been explained.
Chemical-Mechanical Polishing of Polymer Films: Comparison of Benzocyclobutene(BCB) and Parylene-N Films by XPS and AFM
Authors: Yang G.-R. , Zhao Y.-P. , Neirynck Jan M. , Murarka Shyam P. , Gutmann Ronald J. 
Published: April 2011

AbstractThe quality of benzocyclobutene (BCB) and Parylene-N (PA-N) films after chemical-mechanical polishing (CMP) is influenced by 3 factors: slurry composition, quality of the as-deposited film or post-deposition treated film, and polishing time. The quality of the films has been investigated by using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). It is shown that the higher the quality of the as-deposited film (or post-deposition treated film), the higher the quality of the polished film. The polishing time has little effect on the surface characteristics of high quality PA-N films, however it has an effect on BCB film. This is attributed to the structure and thermal-stability and higher chemical resistance of PA-N. The RMS surface roughness measured by AFM, for as-deposited PA-N is 90Å. The roughness after CMP processes is greater than 200Å. The roughness for as-spin-coated and polished BCB film is 5A, and 20Å, respectively. The morphology of the PA-N film, either as-deposited or polished, is not as good as the BCB film. A slurry which is good for BCB polishing is not good for PA-N polishing, and vice versa. These results indicate that the nature of the polymer film, including its chemical structure as well as the quality of the as-deposited/post-deposition treated film, plays an important role in polymer CMP.
Low-k Dielectric Integration Cost Modeling
Authors: Korczynski Ed 
Published: April 2011

AbstractThe wide variety of low-k dielectric materials and processes for ULSI interconnection were sorted to create generic process flows. Average material and equipment costs were then used as inputs to a generic cost-per-wafer (CPW) model for dielectric deposition (not including the costs of dielectric CMP, metallization, or lithography). The model outputs are internally consistent, and useful for comparison of similar processes.