28 Result(s)
within
J Halbritter
Characterization and Evaluation of Materials
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Article
High Frequency Transport Properties of YBCO: Extrinsic Versus Intrinsic d-Wave Properties
In good superconducting YBCO films, the surface impedance Z(T,ω,B)=Zint(T,ωB)+Zres(T,ωB) is dominated for T T c/2 and B∼0 by intrinsic properties, which are difficult to improve. B...
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Article
Metal-Insulator Transition (MIT), Defects, and Percolative Transport in HTS
HTS as layered, doped Mott insulators close to the Metal-Insulator Transition (MIT) become insulating at 6.5 kΩ per CuO-plane at n L ≤ 1021/cm3 localized states. The MIT occurs exponentially around point defects ...
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Article
Corrosion and surface spectroscopies of high-temperature superconductors
Crucial spectroscopic high-temperature superconductor (HTS) information is based on surface methods, like scanning tunneling spectroscopy (STS) or angle-resolved photo-emission spectroscopy (ARPES). But, typic...
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Article
Pseudogap and Transport in HTS
Perpendicular transport is one of the key factors to HTS superconductivity, sampling the quasi-insulating blocking layer, separating the conducting CuO-planes, and driving the metal–insulator transition (MIT) ...
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Article
Charge transfer via interfaces, especially of nanoscale materials
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Article
Resonant Tunneling, Pseudo-Gap, and Charge Dynamics in Cuprate Superconductors
The quasi-two-dimensional, metallic conduction in the CuO2 planes and activated out-of-plane conduction seem typical for most of the cuprate superconductors. The counteraction of overlap and charging energies ΔU*...
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Article
Tunnel channels, spectroscopy and imaging in STM
φ/?≈5.1/nmfor a tunnel with barrier height φ≈1 eV are given for surfaces covered by water, air or vacuum. Despite the n=1,2,3 intermediate states and their charging, imaging down to atomic resolution is achiev...
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Article
YBa2Cu3O7-δ single crystals revisited: Scanning probe data on very pure samples grown in BaZrO3 crucibles
Cu3O7-δ (YBCO) single crystals grown in BaZrO3 crucibles by scanning and friction force microscopy (SFM, FFM) as well as by scanning tunneling microscopy (STM) and angle resolved X-ray photo-electron spectroscopy...
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Article
Nonlinear surface impedance in “low” and “high”T c superconductors
The degradation of the surface impedanceZ = R + iX with rf power is a principal limit for measurements and applications. Such nonlinearities occur for normal conducting cavities by heating or electron loading. Bu...
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Article
Resonant tunneling and perpendicular conduction in cuprate conductors with varying O-content
Anisotropy is inherent to layered cuprates with conduction mainly confined to the CuO2-planes, claimed to be the source of superconductivity. Resonant tunnel exchange for conduction parallel and perpendicular to ...
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Article
Temperature dependence of surface impedance Z(T, ω) and mean free paths I(T) of YBCO-superconductors
The surface impedance Z(T,ω) at 10 and 145 GHz and between 4 and 300 K is obtained experimentally. Z(Ta≤T≤Tc) is quantitatively fitted by the BCS theory with a mean free path I(T) increasing rapidely below Tc. Th...
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Article
Granular superconductors and their intrinsic and extrinsic surface impedance
High-frequency experiments depend sensitively on homogeneous and inhomogeneous “defects” in the normal and superconducting state. As homogeneous effects, the intrinsic scattering time is of great theoretical i...
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Article
Interface studies on magnetron-sputtered SnO2-films
Thin SnO2 films have been prepared for H2-gas sensor application by RF magnetron sputtering onto different SiO2 based glasses. ARXPS and sputter-AES measurements have been performed to evaluate the compounds at S...
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Article
ARXPS-analysis and morphology of sputtered nanocrystalline TiC/SiC coatings
ARXPS (angle resolved X-ray photoelectron spectroscopy) measurements are used to obtain informations about surfaces and grain boundaries. Data acquired from nanocrystalline carbidic hard coatings have been emp...
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Article
ARXPS-analysis of sputtered TiC, SiC and Ti0.5Si0.5C layers
TiC, SiC and Ti0.5Si0.5C layers have been deposited by magnetron sputtering in Argon at bias voltages between 0 and 1500 V. AES and ARXPS analyses show that TiC and Ti0.5Si0.5C, at bias voltages below 1000 V, are...
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Article
Effect of the Weak Links on the Surface Resistance of YBa2Cu3Ox Bulk Material
Dc magnetic field, temperature, and magnetic history dependencies of the millimeter-wave surface resistance have been measured in high quality grain-aligned and in polycrystalline YBa2Cu3Ox bulk material. The mea...
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Article
On Extrinsic Effects in the Surface Impedance of Cuprate Superconductors
Presently, the rf surface impedance Z of cuprate superconductors is still shrinking with material improvements, which is shown clearly by Z = Z1+Zres still dominated by extrinsic properties summarized in Zres. We...
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Article
On intrinsic and extrinsic effects in the surface impedance of cuprate superconductors
Surface impedance measurements in the normal and superconducting state are an excellent method to study conduction electron dynamics and extended defects. Electron dynamics show up most clearly in the relaxati...
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Article
Submillimeter surface impedance and relaxation: A case study of quasi-two-dimensional YBa2Cu3Ox
Surface impedance measurements in the normal and superconducting state are an excellent method to study the conduction electron dynamics in metals. This holds especially in the relaxation range, i.e., for dist...
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Article
The surface impedance of superconductors and normal conductors: The Mattis-Bardeen theory
The contribution of the Mattis-Bardeen theory to the understanding of the surface impedance of superconductors and normal conductors is reviewed. The early theoretical and experimental studies of the surface i...
