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Articles 3121 - 3150 of 3535

Full-Text Articles in Nanoscience and Nanotechnology

The Quest For Stronger, Tougher Materials: A Letter And A Response, Robert O. Ritchie, Yuris A. Dzenis Apr 2008

The Quest For Stronger, Tougher Materials: A Letter And A Response, Robert O. Ritchie, Yuris A. Dzenis

Nebraska Center for Materials and Nanoscience: Faculty Publications

Dr. Ritchie writes: "The perspective “Structural Nanocomposites” (Y. Dzenis, 25 January, p. 419) describes a quest for improved structural materials and indicates that composites with nanoscale reinforcements would have “exceptional mechanical properties.” Is this true?

Why would reinforcements that are small in size or volume offer any particular benefit over larger-scale reinforcements? As the Perspective correctly asserts, if the composite material is to be used for a small-volume structure, clearly the reinforcements must also be small. In addition, small-volume reinforcements are stronger, as has been known since the early days of research on whiskers (1). In this regard, reinforcement by …

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Gold Nanorod-Mediated Photothermolysis Induces Apoptosis To Macrophages Via Damage Of Mitochondria, Ling Tong, Ji-Xin Cheng Apr 2008

Gold Nanorod-Mediated Photothermolysis Induces Apoptosis To Macrophages Via Damage Of Mitochondria, Ling Tong, Ji-Xin Cheng

Birck Poster Sessions

Alterations in macrophage functions contribute to a variety of autoimmune and inflammatory diseases. Diagnosis and eradication of activated macrophages is becoming a valid pharmaceutical target. In this work, gold nanorods conjugated with arginine-rich peptides were applied as theragonosis agents to detect activated macrophages via two-photon luminescence (TPL) and subsequent eradicate through optical hyperthermia. Functionalized gold nanorods could be selectively internalized by activated macrophages in live animals 0.5 h after intraperitoneal (i.p.) injection. Apoptosis of macrophage was induced under proper irradiation conditions to reduce secondary inflammation, through mitochondria-dependent pathway.

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Water-Soluble Iron Oxide Nanoparticles For Nanomedicine, Christy L. Cooper, Lisa M. Reece, J Key, Donald E. Bergstrom, James F. Leary Apr 2008

Water-Soluble Iron Oxide Nanoparticles For Nanomedicine, Christy L. Cooper, Lisa M. Reece, J Key, Donald E. Bergstrom, James F. Leary

Birck Poster Sessions

Monodisperse iron oxide nanoparticles (MION) are easily synthesized in organic solvents for industrial applications. However, biological applications require that the particles by readily dispersed in aqueous solutions. To improve their dispersion in aqueous solution, MION particles can be conjugated to water soluble polymers. These water soluble particles can then be used for nanomedicine, which utilizes nanometer scale constructs to treat diseases at the cellular level. Here we report the synthesis of a monodisperse iron oxide nanoparticle construct for breast cancer applications.

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Interfaces, Volume 10, Issue 1 - Spring 2008 Apr 2008

Interfaces, Volume 10, Issue 1 - Spring 2008

INTERFACES: Newsletter of the Nebraska Center for Materials and Nanoscience

CONTENTS
From the Director
Facility Focus: Nano-Fabrication Facility
Recent Achievements of Center Researchers
Magnetic Nanoclusters Put in Order – Insights with Scanning Tunneling Microscopy
NCMN Welcomes Eva Franke Schubert
Research Spotlight: Barry Cheung
UNL Hosts 54th Annual Midwest Solid State Conference
Published Books
Engineers Part of $9 Million Project Studying Cell Context of Genes

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Outperforming The Conventional Scaling Rules In The Quantum-Capacitance Limit, Joachim Knoch, W Riess, Joerg Appenzeller Apr 2008

Outperforming The Conventional Scaling Rules In The Quantum-Capacitance Limit, Joachim Knoch, W Riess, Joerg Appenzeller

Other Nanotechnology Publications

We present a study on the scaling behavior of field-effect transistors in the quantum-capacitance limit (QCL). It will be shown that a significant performance improvement in terms of the power delay product can be obtained in devices scaled toward the QCL. As a result, nanowires or nanotubes exhibiting a 1-D transport are a premier choice as active channel materials for transistor devices since the QCL can be attained in such systems.

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Tailoring Magnetic Anisotropy At The Ferromagnetic/Ferroelectric Interface, Chun-Gang Duan, Julian P. Velev, Renat F. Sabirianov, Wai-Ning Mei, Sitaram Jaswal, Evgeny Y. Tsymbal Mar 2008

Tailoring Magnetic Anisotropy At The Ferromagnetic/Ferroelectric Interface, Chun-Gang Duan, Julian P. Velev, Renat F. Sabirianov, Wai-Ning Mei, Sitaram Jaswal, Evgeny Y. Tsymbal

Nebraska Center for Materials and Nanoscience: Faculty Publications

It is predicted that magnetic anisotropy of a thin magnetic film may be affected by the polarization of a ferroelectric material. Using a Fe/BaTiO3 bilayer as a representative model and performing first-principles calculations, we demonstrate that a reversal of the electric polarization of BaTiO3 produces a sizable change in magnetic anisotropy energy of Fe films. Tailoring the magnetic anisotropy of a nanomagnet by an adjacent ferroelectric material may yield entirely new device concepts, such as electric-field controlled magnetic data storage.

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Nano-Mechanical Properties Of Heat Inactivated Bacillus Anthracis And Bacillus Thuringiensis Spores, Jessica L. Poindexter Mar 2008

Nano-Mechanical Properties Of Heat Inactivated Bacillus Anthracis And Bacillus Thuringiensis Spores, Jessica L. Poindexter

Theses and Dissertations

B. thuringiensis spores must have similar properties to B. anthracis spores to be a good simulant in counter-proliferation studies. In particular, they must behave in a similar way when exposed to high temperatures for short periods of time as would be caused by an explosion. This research project compares surface elasticities for four different spore sample types, B. anthracis spores, heat inactivated B. anthracis spores, B. thuringiensis spores, and heat inactivated B. thuringiensis spores. Heat inactivated spores were exposed to a temperature just high enough that no spores were observed to germinate. Elasticity values for the spore surfaces were determined …

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A Mems Light Modulator Based On Diffractive Nanohole Gratings, Jack L. Skinner, A. Alec Talin, David A. Horsley Mar 2008

A Mems Light Modulator Based On Diffractive Nanohole Gratings, Jack L. Skinner, A. Alec Talin, David A. Horsley

Mechanical Engineering

We present the design, fabrication, and testing of a microelectromechanical systems (MEMS) light modulator based on pixels patterned with periodic nanohole arrays. Flexure-suspended silicon pixels are patterned with a two dimensional array of 150 nm diameter nanoholes using nanoimprint lithography. A top glass plate assembled above the pixel array is used to provide a counter electrode for electrostatic actuation. The nanohole pattern is designed so that normally-incident light is coupled into an in-plane grating resonance, resulting in an optical stop-band at a desired wavelength. When the pixel is switched into contact with the top plate, the pixel becomes highly reflective. …

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Structural Identification Of Cubic Iron-Oxide Nanocrystal Mixtures: X-Ray Powder Diffraction Versus Quasi-Kinematic Transmission Electron Microscopy, Peter Moeck Mar 2008

Structural Identification Of Cubic Iron-Oxide Nanocrystal Mixtures: X-Ray Powder Diffraction Versus Quasi-Kinematic Transmission Electron Microscopy, Peter Moeck

Physics Faculty Publications and Presentations

Two novel (and proprietary) strategies for the structural identification of a nanocrystal from either a single high-resolution (HR) transmission electron microscopy (TEM) image or a single precession electron diffraction pattern are proposed and their advantages discussed in comparison to structural fingerprinting from powder X-ray diffraction patterns. Simulations for cubic magnetite and maghemite nanocrystals are used as examples.

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An Ultrahigh Vacuum Complementary Metal Oxide Silicon Compatible Nonlithographic System To Fabricate Nanoparticle-Based Devices, Arghya Banerjee, Biswajit Das Mar 2008

An Ultrahigh Vacuum Complementary Metal Oxide Silicon Compatible Nonlithographic System To Fabricate Nanoparticle-Based Devices, Arghya Banerjee, Biswajit Das

Electrical & Computer Engineering Faculty Research

Nanoparticles of metals and semiconductors are promising for the implementation of a variety of photonic and electronic devices with superior performances and new functionalities. However, their successful implementation has been limited due to the lack of appropriate fabrication processes that are suitable for volume manufacturing. The current techniques for the fabrication of nanoparticles either are solution based, thus requiring complex surface passivation, or have severe constraints over the choice of particle size and material. We have developed an ultrahigh vacuum system for the implementation of a complex nanosystem that is flexible and compatible with the silicon integrated circuit process, thus …

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A Study On Supercapacitor Based On Aligned Carbon Nanotubes, Xiao-Yan Ye, Yan-Zhi Wang, Hai-Yan Song, Zhuo Sun, Pin-Gang He, Yu-Zhi Fang Feb 2008

A Study On Supercapacitor Based On Aligned Carbon Nanotubes, Xiao-Yan Ye, Yan-Zhi Wang, Hai-Yan Song, Zhuo Sun, Pin-Gang He, Yu-Zhi Fang

Journal of Electrochemistry

Large scale vertically aligned carbon nanotubes(ACNTs) with uniform length and diameter were prepared by the pyrolysis of iron(Ⅱ) phthalocyanine at low pressure.The ACNTs were activated by electrolyte-activation,acid-activation or electrochemical activation.The performance of the capacitor based on activated ACNTs was characterized by cyclic voltammograms which was of rectangular shape,impedence spectroscopy in which the phase is above 80° and the result specific capacitance was 16～32 F/g,which suggest that the ACNTs are the promising material for the supercapacitor.

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In Situ Measurement Of Chloride Concentration And Ph Distribution In The Crevice During The Crevice Corrosion Of Copper Electronic Board, Min Zhang, Xiang-Dong Zhuo, Chang-Jian Lin Feb 2008

In Situ Measurement Of Chloride Concentration And Ph Distribution In The Crevice During The Crevice Corrosion Of Copper Electronic Board, Min Zhang, Xiang-Dong Zhuo, Chang-Jian Lin

Journal of Electrochemistry

Although the crevice corrosion of metals had been extensively studied in the past years,it remained lack of direct experimental information of the micro chemical environments and electrochemical conditions inside the corroding crevice.The distribution of chloride concentration and local pH in the occluded area are the most crucial factors in development of crevice corrosion.The array probes in one dimension of Ag/AgCl and IrO2 array were developed in this work to in situ follow the distribution of chloride concentration and local pH in the occluded area during the crevice corrosion propagation.Based on a designed simulated crevice corrosion system in 0.5mol/L NaCl …

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Determination Of The Eigenstates And Wavefunctions Of A Single Gated As Donor, Gabriel P. Lansbergen, R. Rahman, C. J. Wellard, P. E. Rutten, J. Caro, I. Woo, N. Colleart, S. Biersemans, Gerhard Klimeck Feb 2008

Determination Of The Eigenstates And Wavefunctions Of A Single Gated As Donor, Gabriel P. Lansbergen, R. Rahman, C. J. Wellard, P. E. Rutten, J. Caro, I. Woo, N. Colleart, S. Biersemans, Gerhard Klimeck

Other Nanotechnology Publications

Current semiconductor devices have been scaled to such dimensions that we need take atomistic approach to understand their operation for nano-electronics. From a bottomsup perspective, the smallest functional element within a nanodevice would be a single (dopant) atom itself. Control and understanding over the eigenenergies and wavefunctions of a single dopant could prove a key ingredient for device technology beyond-CMOS. Here, we will discuss the eigenlevels of a single As donor in a three terminal configuration. The donor is incorporated in the channel of prototype transistors called FinFETs. The measured eigenlevels are shown to consist of levels associated with the …

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Nanopatterning Using Nsom Probes Integrated With High Transmission Nanoscale Bowtie Aperture, Nicholas Murphy-Dubay, Liang Wang, Edward C. Kinzel, Sreemanth Mv Uppuluri, Xianfan Xu Feb 2008

Nanopatterning Using Nsom Probes Integrated With High Transmission Nanoscale Bowtie Aperture, Nicholas Murphy-Dubay, Liang Wang, Edward C. Kinzel, Sreemanth Mv Uppuluri, Xianfan Xu

Birck and NCN Publications

Nanoscale ridge aperture antennas have been shown to have high transmission efficiency and confined nanoscale radiation in the near field region compared with regularly-shaped apertures. The radiation enhancement is attributed to the fundamental electric-magnetic field propagating in the TE10 mode concentrated in the gap between the ridges. This paper reports experimental demonstration of field enhancement using such ridge antenna apertures in a bowtie shape for the manufacture of nanometer size structures using an NSOM (near field scanning optical microscopy) probe integrated with nanoscale bowtie aperture. Consistent lines with width of 59 nm and as small as 24 nm have be …

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Externally Assembled Gate-All-Around Carbon Nanotube Field-Effect Transistor, Zhihong Chen, Damon Farmer, Sheng Xu, Roy Gordon, Phaedon Avouris, Joerg Appenzeller Feb 2008

Externally Assembled Gate-All-Around Carbon Nanotube Field-Effect Transistor, Zhihong Chen, Damon Farmer, Sheng Xu, Roy Gordon, Phaedon Avouris, Joerg Appenzeller

Other Nanotechnology Publications

In this letter, we demonstrate a gate-all-around single-wall carbon nanotube field-effect transistor. This is the first successful experimental implementation of an off-chip gate and gate-dielectric assembly with subsequent deposition on a suitable substrate. The fabrication process and device measurements are discussed in the letter. We also argue in how far charges in the gate oxide are responsible for the observed nonideal device performance.

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Carbon Nanotubes For High-Performance Electronics - Progress And Prospect, Joerg Appenzeller Feb 2008

Carbon Nanotubes For High-Performance Electronics - Progress And Prospect, Joerg Appenzeller

Other Nanotechnology Publications

Carbon nanotube devices offer intrinsic advantages for high-performance logic device applications. The ultrasmall body of a carbon nanotube-the tube diameter-is the key feature that should allow aggressive channel length scaling, while the intrinsic transport properties of the nanotube ensure at the same time high on-currents. in addition, the narrowness of the tube is critical to implementation of novel device concepts like the tunneling transistor. By understanding the unique capabilities of carbon nanotubes and using them in unconventional designs, novel nanoelectronic applications may become feasible. However, much better control of materials quality must be obtained, and new fabrication processes must be …

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Influence Of Phonon Scattering On The Performance Of P-I-N Band-To-Band Tunneling Transistors, Siyuranga O. Koswatta, Mark S. Lundstrom, Dmitri E. Nikonov Jan 2008

Influence Of Phonon Scattering On The Performance Of P-I-N Band-To-Band Tunneling Transistors, Siyuranga O. Koswatta, Mark S. Lundstrom, Dmitri E. Nikonov

Other Nanotechnology Publications

Power dissipation has become a major obstacle in performance scaling of modern integrated circuits and has spurred the search for devices operating at lower voltage swing. In this letter, we study p-i-n band-to-band tunneling field effect transistors taking semiconducting carbon nanotubes as the channel material. The on current of these devices is mainly limited by the tunneling barrier properties, and phonon-scattering has only a moderate effect. We show, however, that the off current is limited by phonon absorption assisted tunneling, and thus is strongly temperature dependent. Subthreshold swings below the 60 mV/decade conventional limit can be readily achieved even at …

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Magnetism Of Laalo3/Srtio3 Superlattices, Karolina Janicka, Julian P. Velev, Evgeny Y. Tsymbal Jan 2008

Magnetism Of Laalo3/Srtio3 Superlattices, Karolina Janicka, Julian P. Velev, Evgeny Y. Tsymbal

Nebraska Center for Materials and Nanoscience: Faculty Publications

First-principles electronic structure calculations are performed to elucidate magnetic properties of LaAlO3 /SrTiO3 heterostructures. We find that TiO2-terminated interfaces are n-type conducting which is consistent with experimental observations. In a (LaAlO3 ) 3 / (SrTiO3)3 superlattice, this interface is magnetic with a magnetic moment on the Ti3+ atom of 0.2 μB, as revealed by the spin-polarized calculations within the local density approximation (LDA). For thicker SrTiO3 layers the magnetic moment decreases and eventually disappears because the electron gas spreads over more than one unit cell, making the …

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Effects Of Ferroelectricity And Magnetism On Electron And Spin Transport In Fe/Batio3 /Fe Multiferroic Tunnel Junctions, Julian P. Velev, Chun-Gang Duan, Kirill D. Belashchenko, Sitaram Jaswal, Evgeny Y. Tsymbal Jan 2008

Effects Of Ferroelectricity And Magnetism On Electron And Spin Transport In Fe/Batio3 /Fe Multiferroic Tunnel Junctions, Julian P. Velev, Chun-Gang Duan, Kirill D. Belashchenko, Sitaram Jaswal, Evgeny Y. Tsymbal

Nebraska Center for Materials and Nanoscience: Faculty Publications

First principles electronic structure and transport calculations are used to demonstrate the impact of the electric polarization on electron and spin transport in Fe/BaTiO3/Fe multiferroic tunnel junctions (MFTJs). We find that the polarization of BaTiO3 reduces the tunneling conductance, as compared to a nonpolarized barrier, due to the change in the electronic structure driven by ferroelectric displacements, similar to that found previously for Pt/BaTiO3/Pt. For the MFTJ, however, this effect has different magnitudes for majority- and minority-spin channels and for parallel and antiparallel orientations of the magnetization of the electrodes. As a result, we find …

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Assembly And Function Of Myosin Ii On Ultraviolet/Ozone Patterned Trimethylchlorosilane Substrates, Madhukar B. Kolli Jan 2008

Assembly And Function Of Myosin Ii On Ultraviolet/Ozone Patterned Trimethylchlorosilane Substrates, Madhukar B. Kolli

Theses, Dissertations and Capstones

The exploration of biomolecular motors in nanotechnological applications has generated much interest in the scientific community. Although the recent progress has been very promising, several requirements have yet to be fulfilled in order for motor proteins to be useful in nanotechnological applications. Here, we present a simple method for patterning myosin II on a microstructured surface. Our findings indicate that UV/ozone treatment can be used to alter the hydrophobicity of trimethyl-chloro-silane (TMCS) coated glass surfaces, to alter protein binding, and effectively produce localized motor activity. Taken together, these data suggest that photoreactive patterning may be useful for the selective localization …

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Morphologies And Kinetics Of A Dewetting Ultrathin Solid Film, Mikhail Khenner Jan 2008

Morphologies And Kinetics Of A Dewetting Ultrathin Solid Film, Mikhail Khenner

Mathematics Faculty Publications

The surface evolution model based on geometric partial differential equation is used to numerically study the kinetics of dewetting and dynamic morphologies for the localized pinhole defect in the surface of the ultrathin solid film with the strongly anisotropic surface energy. Depending on parameters such as the initial depth and width of the pinole, the strength of the attractive substrate potential and the strength of the surface energy anisotropy, the pinhole may either extend to the substrate and thus rupture the film, or evolve to the quasiequilibrium shape while the rest of the film surface undergoes phase separation into a …

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Enhanced Stability Of A Dewetting Thin Liquid Film In A Single-Frequency Vibration Field, Mikhail Khenner Jan 2008

Enhanced Stability Of A Dewetting Thin Liquid Film In A Single-Frequency Vibration Field, Mikhail Khenner

Mathematics Faculty Publications

Dynamics of a thin dewetting liquid film on a vertically oscillating substrate is considered. We assume moderate vibration frequency and large (compared to the mean film thickness) vibration amplitude. Using the lubrication approximation and the averaging method, we formulate the coupled sets of equations governing the pulsatile and the averaged fluid flows in the film, and then derive the nonlinear amplitude equation for the averaged film thickness. We show that there exists a window in the frequency-amplitude domain where the parametric and shear-flow instabilities of the pulsatile flow do not emerge. As a consequence, in this window the averaged description …

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Enhanced Stability Of A Dewetting Thin Liquid Film In A Single-Frequency Vibration Field, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev Jan 2008

Enhanced Stability Of A Dewetting Thin Liquid Film In A Single-Frequency Vibration Field, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mathematics Faculty Publications

Dynamics of a thin dewetting liquid film on a vertically oscillating substrate is considered. We assume moderate vibration frequency and large (compared to the mean film thickness) vibration amplitude. Using the lubrication approximation and the averaging method, we formulate the coupled sets of equations governing the pulsatile and the averaged fluid flows in the film, and then derive the nonlinear amplitude equation for the averaged film thickness. We show that there exists a window in the frequency-amplitude domain where the parametric and shear-flow instabilities of the pulsatile flow do not emerge. As a consequence, in this window the averaged description …

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Enhanced Stability Of A Dewetting Thin Liquid Film In A Single-Frequency Vibration Field, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev Jan 2008

Enhanced Stability Of A Dewetting Thin Liquid Film In A Single-Frequency Vibration Field, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mathematics Faculty Publications

Dynamics of a thin dewetting liquid film on a vertically oscillating substrate is considered. We assume moderate vibration frequency and large (compared to the mean film thickness) vibration amplitude. Using the lubrication approximation and the averaging method, we formulate the coupled sets of equations governing the pulsatile and the averaged fluid flows in the film, and then derive the nonlinear amplitude equation for the averaged film thickness. We show that there exists a window in the frequency-amplitude domain where the parametric and shear-flow instabilities of the pulsatile flow do not emerge. As a consequence, in this window the averaged description …

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Morphologies And Kinetics Of A Dewetting Ultrathin Solid Film, Mikhail Khenner Jan 2008

Morphologies And Kinetics Of A Dewetting Ultrathin Solid Film, Mikhail Khenner

Mathematics Faculty Publications

The surface evolution model based on geometric partial differential equation is used to numerically study the kinetics of dewetting and dynamic morphologies for the localized pinhole defect in the surface of the ultrathin solid film with the strongly anisotropic surface energy. Depending on parameters such as the initial depth and width of the pinole, the strength of the attractive substrate potential and the strength of the surface energy anisotropy, the pinhole may either extend to the substrate and thus rupture the film, or evolve to the quasiequilibrium shape while the rest of the film surface undergoes phase separation into a …

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Enhanced Blocking Temperature And Isothermal Control Of Hysteresis Loop Shifts In Co/Nio/[Co/Pt] Heterostructures With Orthogonal Easy Axes, A. Baruth, Shireen Adenwalla Jan 2008

Enhanced Blocking Temperature And Isothermal Control Of Hysteresis Loop Shifts In Co/Nio/[Co/Pt] Heterostructures With Orthogonal Easy Axes, A. Baruth, Shireen Adenwalla

Nebraska Center for Materials and Nanoscience: Faculty Publications

Heterostructures of Co 4 nm/NiO 1.1 nm/[Co 0.4 nm/Pt 0.6 nm] with mutually orthogonal easy axes allow for isothermal tuning of the hysteresis loop shifts along the applied field axis at room temperature, as well as displaying a greatly enhanced blocking temperature. The loop shifts can be varied up to 35 Oe through the application of moderate dc magnetic fields of 3 kOe. The presence of the [Co/Pt] multilayer with perpendicular anisotropy is responsible for a significant enhancement of the blocking temperature. For this thickness of NiO, the blocking temperature is expected to be well below 50 K, in contrast …

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A Low-Temperature Specific Heat Study Of Giant Dielectric Constant Materials, C. P. Sun, Jianjun Liu, J.-Y. Lin, Chun-Gang Duan, Wao-Ning Mei, H. D. Yang Jan 2008

A Low-Temperature Specific Heat Study Of Giant Dielectric Constant Materials, C. P. Sun, Jianjun Liu, J.-Y. Lin, Chun-Gang Duan, Wao-Ning Mei, H. D. Yang

Nebraska Center for Materials and Nanoscience: Faculty Publications

A low-temperature specific heat study has been performed on the insulating giant dielectric constant material CaCu3Ti4O12 and two related compounds, Bi2/3Cu3Ti4O12 and La0.5Na0.5Cu3Ti4O12, from 0.6 to 10 K. From analyzing the specific heat data in a very low-temperature range, 0.6–1.5 K, and moderately low-temperature range, 1.5–5 K, in addition to the expected Debye terms, we observed significant contributions originating from the linear and Einstein terms, which we attributed as the manifestation of low-lying elementary excitations due to lattice …

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Nano Quasicrystal Formation And Local Atomic Structure In Zr––Pd And Zr––Pt Binary Metallic Glasses, Junji Saida, Takashi Sanada, Shigeo Sato, Muneyuki Imafuku, Chunfei Li, Akihisa Inoue Jan 2008

Nano Quasicrystal Formation And Local Atomic Structure In Zr––Pd And Zr––Pt Binary Metallic Glasses, Junji Saida, Takashi Sanada, Shigeo Sato, Muneyuki Imafuku, Chunfei Li, Akihisa Inoue

Center for Electron Microscopy and Nanofabrication Publications and Presentations

Formation of the nanoscale icosahedral quasicrystalline phase (I-phase) in the melt-spun Zr70Pd30 and Zr80Pt20 binary metallic glasses were reported. Local atomic structure in the glassy and quasicrystal (QC)-formed states were also analyzed by XRD and EXAFS measurements in order to investigate the formation mechanism of QC phase. The distorted icosahedral-like local structure can be identified around Zr atom in the Zr70Pd30 metallic glass. In the QC formation process, a change of local environment around Zr is detected, in which the approximately one Zr atom substitutes for one Pd atom. In contrast, …

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Polaron And Phonon Properties In Proton Intercalated Amorphous Tungsten Oxide Thin Films, M. Saenger, T. Hoing, Brian W. Robertson, R. Billa, Tino Hofmann, Eva Schubert, Mathias Schubert Jan 2008

Polaron And Phonon Properties In Proton Intercalated Amorphous Tungsten Oxide Thin Films, M. Saenger, T. Hoing, Brian W. Robertson, R. Billa, Tino Hofmann, Eva Schubert, Mathias Schubert

Nebraska Center for Materials and Nanoscience: Faculty Publications

We report on the evolution of the polaron and phonon mode properties in amorphous tungsten oxide thin films measured by spectroscopic ellipsometry in the infrared to ultraviolet spectral regions as a function of the intercalated proton density. A parametric physical model dielectric function is presented, which excellently describes the ellipsometry data over a large intercalated charge-density range. Upon increased amounts of intercalated charge we observe a strong increase in the polaron absorption in the visible spectral range, a decrease in the infrared W–O bond polarity, and an increase in the W=O bond polarity. Our findings support the oxygen-extraction model as …

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Geometrical Interpretation And Simulation Of Holz Patterns, Xingzhong Li Jan 2008

Geometrical Interpretation And Simulation Of Holz Patterns, Xingzhong Li

Nebraska Center for Materials and Nanoscience: Faculty Publications

Higher-order Laue zone (HOLZ) pattern is very useful in measurement of crystalline lattice parameters, strain and composition variation in a small area of sample. Bloch dynamical theory on convergent-beam electron diffraction (CBED), including the formation of HOLZ lines, has been well developed and documented in Ref. and references therein. Although CBED patterns and included HOLZ lines are best modeled using a dynamical formulation, models based on a geometrical interpretation for the HOLZ-line positions have remained in widespread use because of their simplicity. Moreover, the geometrical interpretation is helpful to understand the formation of HOLZ lines for beginners. The geometrical interpretation …

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