2019, Buchkov, K., Valkovski, M., Gajda, D., Nenkov, K., Nazarova, E.

The weak links effects are one of the main challenges for effective power applications of high temperature superconducting materials. Studies of these effects help for their better understanding and subsequent improvement. An overview analysis of the intergranular properties of cuprate (Y0.8Ca0.2Ba2Cu3O7-δ) and iron-based chalcogenide (FeSe0.5Te0.5) polycrystalline samples was carried out, by means of series of electro-transport experiments at different magnetic fields. The temperature evolution of the Josephson coupling and intrinsic superconductivity effects for the both systems was constructed. The FeSe0.5Te0.5 compound shows very stable and superior behavior compared to Y0.8Ca0.2BCO up to the highest magnetic fields (14T) used. We have explored FeSe0.5Te0.5 Josephson weak links influence (as a non-linear process) over the resistive transition using different AC current amplitudes and applying the sensitive AC transport third harmonics technique.

2015, Schütte, Bernd, Vrakking, Marc J. J., Rouzée, Arnaud

We report on the observation of a transient C4+ ion charge state in nanoplasmas produced by the interaction of intense near-infrared (NIR) laser pulses with CH4 clusters. The underlying dynamics are studied by pump-probe spectroscopy, which reveals that the ion charge states are lowered by electron-ion recombination. Furthermore, we present direct evidence that autoionization of multiply-excited ions plays an important role in expanding nanoplasmas, in contrast to models that neglect quantum phenomena.

2014, Asenova, I., Manova, D., Mändl, S.

In this paper we investigate the possibility of incorporating nitrogen into amorphous, photocatalytic TiO2 thin films, prepared at room temperature, during the growth process. The aim is to reduce the bandgap of the UV active thin films. Physical vapor deposition experiments employing a titanium vacuum arc with gas backfill ranging from pure oxygen to pure nitrogen, are carried out. The resulting films are characterized for chemical composition, phase composition, optical properties and hydrophilicity in order to determine a correlation between gas composition and thin film properties. The experimental results point that a visible change in the band structure of the deposited layers is achieved.

2015, Schütte, Bernd, Arbeiter, Mathias, Fennel, Thomas, Jabbari, Ghazal, Gokhberg, Kirill, Kuleff, Alexander I., Vrakking, Marc J. J., Rouzée, Arnaud

We report on the observation of a novel intracluster Coulombic decay process following Rydberg atom formation in clusters ionized by intense near-infrared fields. A new decay channel emerges, in which a Rydberg atom relaxes to the ground state by transferring its excess energy to a weakly bound electron in the environment that is emitted from the cluster. We find evidence for this process in the electron spectra, where a peak close to the corresponding atomic ionization potential is observed. For Ar clusters, a decay time of 87 ps is measured, which is significantly longer than in previous time-resolved studies of interatomic Coulombic decay.