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81.
We have investigated the temperature dependent electrical resistivity, ρ(T), of Ag(100 nm)/Al(10 nm) bilayers grown on Si(111) and quartz substrates using molecular beam epitaxy (MBE). Bilayers grown on Si exhibited an anomalous negative temperature coefficient of resistivity (TCR) in the temperature range of 140-165 K of the ρ(T) plot. However, at temperatures below and above this negative TCR region, ρ(T) exhibited a characteristic positive TCR of metallic alloys. No such resistive anomaly was observed for the bilayers grown on quartz substrates. The observed resistive anomaly could be qualitatively explained by assuming two parallel conduction channels, that is, one at the interface having high Si content and obeying the polaronic behavior at <165 K and another far away from the interface having almost no Si impurity and thus exhibiting pure metallic behavior down to 4 K. In addition, bilayers exhibited a sharp resistive transition at ∼6.5 K, indicating a possibility of a new Ag-Al alloy being a superconducting material. 相似文献
82.
83.
B.C. Jamalaiah 《Journal of luminescence》2009,129(4):363-787
Room temperature visible and near infrared optical absorption and emission spectra of Sm3+-doped lead borate titanate aluminum fluoride (LBTAF) glasses with molar composition (50−x) PbO−30H3BO3−10TiO2−10AlF3−xSm2O3 (x=0.1, 0.5, 1.0 and 2.0) have been analyzed. Energy parameters for the 4f5 electronic configuration of Sm3+: LBTAF glasses have been evaluated using free-ion Hamiltonian model. The experimental oscillator strengths of absorption bands have been used to determine the J-O parameters. Fluorescence spectra were recorded by exciting the samples with 402 nm. Using the J-O parameters and luminescence data, the radiative transition probabilities (AR), branching ratios (βR) and stimulated emission cross-sections (σe) were obtained. The decay curves of 4G5/2→6H7/2 transition exhibit single exponential for lower concentration (0.1 mol%) and non-exponential for higher concentrations. This concentration quenching has been attributed to the energy transfer through cross-relaxation between Sm3+ ions. From the values of the radiative parameters, it is concluded that 1.0 mol% Sm3+-doped LBTAF glass may be used for laser active medium with emission wavelength at 600 nm. 相似文献
84.
Matthew R. Buckley Seong Youl Choi Kentarou Mawatari Hitoshi Murayama 《Physics letters. [Part B]》2009
Determining the spin of new particles is critical in identifying the true theory among various extensions of the Standard Model at the next generation of colliders. Quantum interference between different helicity amplitudes was shown to be effective when the final state is fully reconstructible. However, many interesting new physics processes allow only for partial reconstruction. In this Letter, we show how the interference effect can be unambiguously extracted even in processes that have two-fold ambiguity, by considering the correlation between two decay planes in e+e− collisions. 相似文献
85.
V.C. Selvaraju S. Asokan V. Srinivasan 《Applied Physics A: Materials Science & Processing》2003,77(1):149-153
The I–V characteristics of bulk As40Te60-xSex and As35Te65-xSex glasses have been studied with a current sweep of 0–18 mA-0, over a wide range of compositions (4≤x≤22). All the glasses
studied showed a threshold electrical switching behaviour. The number of switching cycles withstood by the samples has been
found to depend on the ON-state current. It is seen that the switching voltages increase with increase in selenium content.
Further, the switching voltages are found to be almost independent of the thickness of the sample (d), in the range 0.18–0.3 mm.
Also, the switching voltages and the number of switching cycles withstood by the samples are found to decrease with temperature.
Received: 6 November 2002 / Accepted: 8 November 2002 / Published online: 29 January 2003
RID="*"
ID="*"Corresponding author. Fax: +91-80/360-0135, E-mail: sasokan@isu.iisc.ernet.in 相似文献
86.
Transverse-energy and charged-particle pseudorapidity densities at midrapidity and their ratio, dET/d|mid/dNch/d|mid, are evaluated in a statistical model with longitudinal and transverse flows for the wide range of colliders, from AGS to RHIC at
= 200 GeV. Evaluations are done at freeze-out parameters obtained from independent fits to observed particle yields and pT spectra. Decays of hadron resonances are treated thoroughly and are included in derivations of dET/d|mid and dNch/d|mid. The predictions of the model agree well with the experimental data. However, some (explicable) overestimation of the ratio has been observed. 相似文献
87.
We analyze the spectra of pions and protons in heavy-ion collisions at relativistic energies from 2 A GeV to 65+65 A GeV by
using a jet-implemented hadron-string cascade model. In this energy region, hadron transverse mass spectra first show softening
until SPS energies, and re-hardening may emerge at RHIC energies. Since hadronic matter is expected to show only softening
at higher energy densities, this re-hardening of spectra can be interpreted as a good signature of the quark-gluon plasma
formation 相似文献
88.
Electron paramagnetic resonance and optical absorption spectra of Cr ions in cadmium phosphate glass
R.V.S.S.N. Ravikumar Ryuichi KomatsuKo. Ikeda A.V. ChandrasekharB.J. Reddy Y.P. ReddyP.S. Rao 《Solid State Communications》2003,126(5):251-253
EPR and optical absorption investigations of chromium doped cadmium phosphate glass are carried out. Crystal field, spin-Hamiltonian and bonding parameters are evaluated. From the results and analyses of the EPR and optical studies, the site symmetry of Cr3+ ion in the glass is ascribed to a distorted octahedron. The bonding parameters suggest the ionic nature of Cr3+ ion with the ligands. 相似文献
89.
New statistical ensembles of classical extreme black holes are introduced. Each ensemble is proven to represent a non extreme, finite temperature black hole. This mean or average black hole is surrounded by a mean electromagnetic field and a so-called apparent matter, which is the large scale trace of the averaged upon small scale fluctuations of the gravitational and electromagnetic fields. However, the total mass and the total charge of space-time is not modified by the averaging. 相似文献
90.
ZnO nanorods and nanonails have been synthesized on silicon wafers by a three-step catalyst-free thermal evaporation method in oxygen atmosphere. All the samples were hexagonal phase ZnO with highly c-axis preferential orientation. Different morphologies of ZnO nanostructures, i.e. ZnO nanorods and two kinds of nanonails, were observed at various temperature regions. Photoluminescence, transmission electron microscopy, and energy-dispersive X-ray spectroscope were employed to elucidate the reason for the formation of such different rod-like structures. The analysis results demonstrated that the caps of nanonails possess a large number of oxygen vacancies, which may play a key role in determining the formation of nanonails and the high intensity of green emission. 相似文献