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Ni, Yan; Zhang, Zhen; Nlebedim, Cajetan I.; Jiles, David C.
Ames Laboratory (AMES), Ames, IA (United States). Funding organisation: USDOE Office of Science - SC, Basic Energy Sciences (BES) (SC-22) (United States)2016
Ames Laboratory (AMES), Ames, IA (United States). Funding organisation: USDOE Office of Science - SC, Basic Energy Sciences (BES) (SC-22) (United States)2016
AbstractAbstract
[en] In this study, we deposited high quality (Sb_1_xBi_x)_2Te_3 on mica substrate by molecular beam epitaxy and investigated their magnetotransport properties. It is found that the average surface roughness of thin films is lower than 2 nm. Moreover, a local maxima on the sheet resistance is obtained with x = 0.043, indicating a minimization of bulk conductivity at this composition. For (Sb_0_._9_5_7Bi_0_._0_4_3)_2Te_3, weak antilocalization with coefficient of -0.43 is observed, confirming the existence of 2D surface states. Moreover Shubnikov-de Hass oscillation behavior occurs under high magnetic field. The 2D carrier density is then determined as 0.81 x 10"1"6 m"-"2, which is lower than that of most TIs reported previously, indicating that (Sb_0_._9_5_7Bi_0_._0_4_3)_2Te_3 is close to ideal TI composition of which the Dirac point and Fermi surface cross within the bulk bandgap. Our results thus demonstrate the best estimated composition for ideal TI is close to (Sb_0_._9_5_7Bi_0_._0_4_3)_2Te_3 and will be helpful for designing TI-based devices
Source
IS-J--8879; OSTIID--1240746; CONTRACT 1201883; AC02-07CH11358; Available from: DOI:10.1063/1.4943156; DOE Accepted Manuscript full text, or the publishers Best Available Version will be available free of charge after the embargo period from OSTI using http://www.osti.gov/pages/biblio/1240746
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Miao, B. F.; Huang, S. Y.; Qu, D.; Chien, C. L.
The Johns Hopkins Univ., Baltimore, MD (United States). Funding organisation: USDOE Office of Science - SC (United States)2016
The Johns Hopkins Univ., Baltimore, MD (United States). Funding organisation: USDOE Office of Science - SC (United States)2016
AbstractAbstract
[en] The Pt/YIG structure has been widely used to study spin Seebeck effect (SSE), inverse spin Hall effect, and other pure spin current phenomena. However, the magnetic proximity effect in Pt when in contact with YIG, and the potential anomalous Nernst effect (ANE) may compromise the spin current phenomena in Pt/YIG. By inserting a Cu layer of various thicknesses between Pt and YIG, we have separated the signals from the SSE and that of the ANE. Here, it is demonstrated that the thermal voltage in Pt/YIG mainly comes from spin current due to the longitudinal SSE with negligible contribution from the ANE
Source
OSTIID--1242967; SC0009390; Available from: DOI:10.1063/1.4941340; DOE Accepted Manuscript full text, or the publishers Best Available Version will be available free of charge after the embargo period from OSTI using http://www.osti.gov/pages/biblio/1242967
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Henriques, Alexandra; Graham, Joseph T.; Landsberger, Sheldon; Ihlefeld, Jon F.; Brennecka, Geoff L.; Brown, Donald W.; Forrester, Jennifer S.; Jones, Jacob L.
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Funding organisation: USDOE National Nuclear Security Administration (NNSA) (United States)2014
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Funding organisation: USDOE National Nuclear Security Administration (NNSA) (United States)2014
AbstractAbstract
[en] Piezoelectric and ferroelectric materials are useful as the active element in non-destructive monitoring devices for high-radiation areas. Here, crystallographic structural refinement (i.e., the Rietveld method) is used to quantify the type and extent of structural changes in PbZr_0_._5Ti_0_._5O_3 after exposure to a 1 MeV equivalent neutron fluence of 1.7 x 10"1"5 neutrons/cm"2. The results show a measurable decrease in the occupancy of Pb and O due to irradiation, with O vacancies in the tetragonal phase being created preferentially on one of the two O sites. Lastly, the results demonstrate a method by which the effects of radiation on crystallographic structure may be investigated
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SAND--2014-15437J; OSTIID--1235928; AC04-94AL85000; Available from: DOI:10.1063/1.4902179; DOE Accepted Manuscript full text, or the publishers Best Available Version will be available free of charge after the embargo period from OSTI using http://www.osti.gov/pages/biblio/1235928
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ALLOYS, BARYONS, CHALCOGENIDES, CRYSTAL DEFECTS, CRYSTAL STRUCTURE, DIELECTRIC MATERIALS, ELECTRICITY, ELEMENTARY PARTICLES, ELEMENTS, ENERGY RANGE, FERMIONS, HADRONS, LEAD COMPOUNDS, MATERIALS, METALS, MEV RANGE, NONMETALS, NUCLEONS, OXIDES, OXYGEN COMPOUNDS, POINT DEFECTS, RADIATION EFFECTS, TITANATES, TITANIUM COMPOUNDS, TRANSITION ELEMENT ALLOYS, TRANSITION ELEMENT COMPOUNDS, ZIRCONATES, ZIRCONIUM COMPOUNDS
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[en] We report a dielectric relaxation in BaTiO3-based ferroelectric thin films of different composition and with several growth modes: sputtering (with and without magnetron) and sol-gel. The relaxation was observed at cryogenic temperatures (T < 100 K) for frequencies from 100 Hz up to 10 MHz. This relaxation activation energy is always lower than 200 meV and is very similar to the relaxation that we reported in the parent bulk perovskites. Based on our Electron Paramagnetic Resonance (EPR) investigation, we ascribe this dielectric relaxation to the hopping of electrons among Ti3+-V(O) charged defects. Being dependent on the growth process and on the amount of oxygen vacancies, this relaxation can be a useful probe of defects in actual integrated capacitors with no need for specific shaping.
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(c) 2013 © 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.; Country of input: International Atomic Energy Agency (IAEA)
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ALKALINE EARTH METAL COMPOUNDS, CHARGED PARTICLES, CRYSTAL DEFECTS, CRYSTAL STRUCTURE, DIELECTRIC MATERIALS, ELECTRICAL EQUIPMENT, ELECTRON TUBES, ELECTRONIC EQUIPMENT, ENERGY, EQUIPMENT, FILMS, IONS, MAGNETIC RESONANCE, MATERIALS, MICROWAVE EQUIPMENT, MICROWAVE TUBES, MINERALS, OXYGEN COMPOUNDS, POINT DEFECTS, RESONANCE, TEMPERATURE RANGE, TITANIUM COMPOUNDS, TRANSITION ELEMENT COMPOUNDS
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Huber, Stefan E.; Mauracher, Andreas; Probst, Michael, E-mail: s.huber@uibk.ac.at, E-mail: Michael.probst@uibk.ac.at, E-mail: s.huber@uibk.ac.at, E-mail: Michael.probst@uibk.ac.at2013
AbstractAbstract
[en] Energetic and geometric aspects of the permeation of the atoms hydrogen to neon neutral atoms through graphene sheets are investigated by investigating the associated energy barriers and sheet deformations. Density functional theory calculations on cluster models, where graphene is modeled by planar polycyclic aromatic hydrocarbons (PAHs), provide the energies and geometries. Particularities of our systems, such as convergence of both energy barriers and deformation curves with increasing size of the PAHs, are discussed. Three different interaction regimes, adiabatic, planar and vertical, are investigated by enforcing different geometrical constraints. The adiabatic energy barriers range from 5 eV for hydrogen to 20 eV for neon. We find that the permeation of oxygen and carbon into graphene is facilitated by temporary chemical bonding while for other, in principle reactive atoms, it is not. We discuss implications of our results for modeling chemical sputtering of graphite
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(c) 2013 Author(s); Country of input: International Atomic Energy Agency (IAEA)
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[en] This work systematically investigated a high-κ Al2O3 material for low temperature wafer-level bonding for potential applications in 3D microsystems. A clean Si wafer with an Al2O3 layer thickness of 50 nm was applied as our experimental approach. Bonding was initiated in a clean room ambient after surface activation, followed by annealing under inert ambient conditions at 300 °C for 3 h. The investigation consisted of three parts: a mechanical support study using the four-point bending method, hermeticity measurements using the helium bomb test, and thermal conductivity analysis for potential heterogeneous bonding. Compared with samples bonded using a conventional oxide bonding material (SiO2), a higher interfacial adhesion energy (∼11.93 J/m2) and a lower helium leak rate (∼6.84 × 10−10 atm.cm3/sec) were detected for samples bonded using Al2O3. More importantly, due to the excellent thermal conductivity performance of Al2O3, this technology can be used in heterogeneous direct bonding, which has potential applications for enhancing the performance of Si photonic integrated devices
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(c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
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Li, Nan; Zhu, Haiye; Wang, Wenyu; Gong, Yu, E-mail: nan.li@bjut.edu.cn2014
AbstractAbstract
[en] A semi-analytical model for a double-plate capacitive proximity sensor is presented according to the effective theory. Three physical models are established to derive the final equation of the sensor. Measured data are used to determine the coefficients. The final equation is verified by using measured data. The average relative error of the calculated and the measured sensor capacitance is less than 7.5%. The equation can be used to provide guidance to engineering design of the proximity sensors
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(c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
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[en] We demonstrate strong evanescent wave amplification by a thin slab of uniaxial μ-near-zero (UMNZ) material. It is found that while retaining the same amplification effect, the slab can be made arbitrarily thin when the negative permeability along the axis of anisotropy approaches zero. Numerical results show that using a single layer of split-ring resonators (SRRs) with its thickness equal three thousandth of the incident wavelength (λ/3000), a subwavelength source distribution with λ/4 resolution can be transferred to a distance of λ/3
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(c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
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[en] We have demonstrated electronic structure and magnetic properties of Cu3, Ag3 and Au3 trimers using a full potential local orbital method in the framework of relativistic density functional theory. We have also shown that the non-relativistic generalized gradient approximation for the exchange-correlation energy functional gives reliable magnetic properties in coinage metal trimers compared to experiment. In addition we have indicated that the spin-orbit coupling changes the structure and magnetic properties of gold trimer while the structure and magnetic properties of copper and silver trimers are marginally affected. A significant orbital moment of 0.21μB was found for most stable geometry of the gold trimer whereas orbital magnetism is almost quenched in the copper and silver trimers
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(c) 2013 Author(s); Country of input: International Atomic Energy Agency (IAEA)
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Kosemura, Daisuke; Mizukami, Yuki; Takei, Munehisa; Numasawa, Yohichiroh; Ogura, Atsushi; Ohshita, Yoshio, E-mail: d_kose@isc.meiji.ac.jp2014
AbstractAbstract
[en] 100-nm-thick nanocrystalline silicon (nano-Si)-dot multi-layers on a Si substrate were fabricated by the sequential repetition of H-plasma surface treatment, chemical vapor deposition, and surface oxidation, for over 120 times. The diameter of the nano-Si dots was 5–6 nm, as confirmed by both the transmission electron microscopy and X-ray diffraction analysis. The annealing process was important to improve the crystallinity of the nano-Si dot. We investigated quantum confinement effects by Raman spectroscopy and photoluminescence (PL) measurements. Based on the experimental results, we simulated the Raman spectrum using a phenomenological model. Consequently, the strain induced in the nano-Si dots was estimated by comparing the experimental and simulated results. Taking the estimated strain value into consideration, the band gap modulation was measured, and the diameter of the nano-Si dots was calculated to be 5.6 nm by using PL. The relaxation of the q ∼ 0 selection rule model for the nano-Si dots is believed to be important to explain both the phenomena of peak broadening on the low-wavenumber side observed in Raman spectra and the blue shift observed in PL measurements
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(c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
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