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    Femtosecond spectroscopy in a nearly optimally doped Fe-based superconductors FeSe0.5Te0.5 and Ba(Fe 1-xCox)2As2/Fe thin film
    (Bristol : Institute of Physics Publishing, 2014) Bonavolontà, C.; Parlato, L.; De, Lisio, C.; Valentino, M.; Pepe, G.P.; Kazumasa, I.; Kurth, F.; Bellingeri, E.; Pallecchi, I.; Putti, M.; Ferdeghini, C.; Ummarino, G.A.; Laviano, F.
    Femtosecond spectroscopy has been used to investigate the quasi-particle relaxation times in nearly optimally doped Fe-based superconductors FeSe 0.5Te0.5 and optimally doped Ba-122 thin films growth on a Fe buffer layer. Experimental results concerning the temperature dependence of the relaxation time of such pnictides both in the superconducting state are now presented and discussed. Modelling the T-dependence of relaxation times an estimation of both electron-phonon constant and superconducting energy gap in the excitation spectrum of both Fe(Se,Te) and Ba-122 compounds is obtained.
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    Cryogenic time-domain multiplexer based on SQUID arrays and superconducting/normal conducting switches
    (Bristol : Institute of Physics Publishing, 2014) Beev, N.; Kiviranta, M.; Van Der Kuur, J.; Bruijn, M.; Brandel, O.; Linzen, S.; Fritzsch, L.; Ahoranta, J.; Penttilä, J.; Roschier, L.
    We have demonstrated the operation of a 12-channel Beyer-style SQUID-based time domain multiplexer. It was manufactured using a fabrication process that is cross-compatible between VTT and IPHT-Jena. The multiplexer consists of twelve 12-SQUID series arrays, each shunted by a Zappe-style interferometer array acting as a flux-controlled superconducting/normal conducting switch. By keeping all switches but one in the superconducting state, it is possible to select one active readout channel at a time. A flux feedback coil common to all SQUID arrays allows realization of a flux-locked loop. We present characteristics of the multiplexer and measurement data from experiments with a 25-pixel X-ray calorimeter array operated at T < 100 mK in a dilution refrigerator.
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    Combinatorial synthesis of (YxGd1-x)Ba2Cu3Ox superconducting thin films
    (Amsterdam [u.a.] : Elsevier, 2012) Kirchner, A.; Erbe, M.; Freudenberg, T.; Hühne, R.; Feys, J.; Van Driessche, I.; Schultz, L.; Holzapfel, B.
    Environmentally friendly water-based YBa2Cu3Ox (YBCO) and GdBa2Cu3Ox (GdBCO) precursor solutions were synthesized to realize thin films by chemical solution deposition. Pure YBCO and GdBCO precursor solutions were used for ink plotting on SrTiO3 substrates and subsequent thermal treatment at the corresponding crystallization temperature. Phase formation of Gd123 requires a higher crystallization temperature of 840 °C compared to the Y123 phase. The critical temperature of YBCO films is about 92 K with a sharp transition into the superconducting state. Micro liter sized ink volumes of YBCO and GdBCO were successfully mixed for two-dimensional ink plotting of a (YxGd1-x)Ba2Cu3Ox film library. A homogeneous surface and no indication of a-axis growth were found in all mixed films.