CELASCO , Edvige

Until now, all existing theories failed to explain peaks in the power noise spectra. Here we focus on the role of correlation among avalanches as the main source of the noise peaks observed. The present theory is based on first principles statistics of elementary events clustered in time-amplitude correlated avalanches. A noise spectral power...

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Vortex avalanche phenomenon enhanced by thermomagnetic instabilities suppresses critical current in MgB2 films. This effect is investigated at 4.2 K by spectral noise power measurements up to 1 kHz with a dc superconducting quantum interference device apparatus. 1/f(gamma) behavior is shown at low frequencies in magnetic fields and feeding...

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The peaked structures of the excess noise observed in many superconducting transition edge sensors are analyzed in both the normalized resistance and the frequency domains. In the framework of our dynamical percolation model we find high amplitude noise peaks in the low normalized resistance range (0.2 approximately) and of much lower amplitude...

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Spectral noise power measurements are reported in a bulk YBa(2)Cu(3)O(7-delta) superconductor at 4.2 K to investigate the flux vortex avalanche processes originated from thermomagnetic instabilitites in an applied magnetic field up to 600 mT and in feeding current close to the critical value. 1/f(gamma) behavior is shown at frequencies below 10...

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We report on a combined high resolution electron energy loss spectroscopy and x-rays photoelectron spectroscopy investigation of the interaction at room temperature of H2O with thin and ultra-thin MgO films grown on Ag(100). We find a strongly enhanced dissociation probability in the monolayer and sub-monolayer regime, indicative of an active...

The interest in thin and ultrathin oxide films is increasing rapidly due to the new properties and the many possible technological applications of such materials. In this frame the interaction with water, a major constituent of our atmosphere, is an essential issue for a better characterization of oxide film-based devices. We report here a...

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The vibrational modes of clean MgO films are investigated vs film thickness by means of high-resolution electron energy-loss spectroscopy. For thin films (20-30 monolayers) we observe, in accord with the literature, the Fuchs-Khewer phonon at 677 cm(-1) and the Wallis mode at 524 cm(-1). For ultrathin films standing wave optical phonons...

SiC-ZrB2 ceramic laminates with different SiC:ZrB2 ratios were prepared by tape casting, binder burnout and pressureless sintering at 2200°C in view of their application in thermal protection systems. Their oxidation behavior in air was investigated by TGA up to 1600°C and by long term oxidation tests at 1500 and 1600°C. Both microstructure and...

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In this work we studied different Schottky contacts to 4H-SiC with the aim to obtain Schottky Barrier diodes (SBDs) and Junction Barrier Schottky diodes (JBS) able to operate at high temperatures, frequencies and power densities with low power losses. Schottky contacts were fabricated using Mo and Mo/Al layers annealed up to 600 °C using a...