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Wyszukujesz frazę "Silva, R." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
Combined Analyses of Ion Beam Synthesized Layers in Porous Silicon
Autorzy:
Ramos, A. R.
Pászti, F.
Horváth, Z. E.
Vázsonyi, É.
Conde, O.
da Silva, M. F.
da Silva, M. R.
Soares, J. C.
Powiązania:
https://bibliotekanauki.pl/articles/2028988.pdf
Data publikacji:
2001-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.10.-i
61.18.Bn
61.43.Gt
68.55.Ln
Opis:
High dose ion implantation was used to form polycrystalline silicide films on porous silicon with different native concentrations of light impurities (C and O). Porous silicon layers severalμm thick were implanted with 170 keV Cr$\text{}^{+}$ ions to fluences of 3×10$\text{}^{17}$ ions/cm$\text{}^{2}$ both at room temperature and 450ºC. Similar samples were implanted with 100 keV Co$\text{}^{+}$ ions to fluences of 2×10$\text{}^{17}$ ions/cm$\text{}^{2}$ at room temperature, 350ºC, and 450ºC. The formed silicide compounds were studied by Rutherford backscattering spectrometry, elastic recoil detection, glancing incidence X-ray diffraction, and four point-probe sheet resistance measurements. Selected Co implanted samples were analysed by cross-section transmission electron microscopy. Results show that the light impurities were partially expelled from the forming silicide layer. Combining cross-section transmission electron microscopy with ion beam methods it was possible to show that, in the implanted region, the porous structure collapses and densifies during implantation, but the underlying porous silicon remains intact. The layer structure, as well as the quality and type of the formed silicide, were found to depend on the original impurity level, implantation temperature, and annealing.
Źródło:
Acta Physica Polonica A; 2001, 100, 5; 773-780
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vortex Motion and Quasiparticle Resistivity in Superconductors at Microwave Frequencies
Autorzy:
Sarti, S.
Amabile, C.
Fastampa, R.
Giura, M.
Silva, E.
Pompeo, N.
Powiązania:
https://bibliotekanauki.pl/articles/2047225.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Nf
74.20.De
74.60.Ge
74.70.Ad
74.72.-h
Opis:
At nonzero frequencies both the normal and superfluid fractions, as well as moving vortices, contribute to the electrical transport, resulting in intricate expressions for the resistivity. We present an extended study of microwave resistivity data measured on YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$, SmBa$\text{}_{2}$ Cu$\text{}_{3}$O$\text{}_{7-δ}$, and MgB$\text{}_{2}$ by means of a broad-band technique between 2 and 20 GHz and of a resonant system at 50 GHz. We discuss the main experimental fingerprints that allow one to identify the relevance of the different contributions from the measured microwave response as a function of frequency, temperature, and magnetic field. We show that the field-dependent superfluid/quasiparticles dynamics cannot be in general neglected with respect to the vortex motion, albeit its relative importance is different in different materials: in high temperature superconductors vortex motion prevails at high fields, but at low fields a significant superfluid/quasiparticle contribution exists (ascribed to the presence of lines of nodes). In MgB$\text{}_{2}$ the two contributions are comparable even at high fields. In this general frame, we derive from the measurements vortex and superfluid parameters in agreement with theoretical predictions and independent measurements.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 87-93
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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