caa a22 4500 445382473 CHVBK 20180317143021.0 cr unu---uuuuu 170323e20110101xx s 000 0 eng 10.1007/s10948-010-0973-8 doi (NATIONALLICENCE)springer-10.1007/s10948-010-0973-8 Andreev Reflection and Granular Superconductivity Features Observed in Mesoscopic Samples Using Amorphous Tungsten Carbide Superconductors [Elektronische Daten] [J. Barzola-Quiquia, S. Dusari, C. Chiliotte, P. Esquinazi] Point-contact Andreev reflection and magnetoresistance measurements were done using amorphous tungsten carbide (WCx) superconductors. Superconducting tips as well as microwires were grown directly under a focused Ga+-ion beam (FIB) on pre-patterned samples. Using e-beam lithography, the electrical contacts were prepared later using a special geometry. Current-voltage measurements as a function of temperature and magnetic field clearly showed the signatures of Andreev reflection. We observed anomalies in the differential conductivity at voltages above the energy gap values. These anomalies can be well understood as due to a weak-link formation with narrow band properties contributing in parallel at the interfaces of the contacts. We also observed Andreev oscillations as a function of magnetic field similar to those found recently in specially prepared normal-superconducting-normal nanostructures and multigraphene samples. In some of the structures, we were able to produce interfaces in which clear granular behavior in a certain temperature region was observed, such as, for example, an anomalous field hysteresis loop compatible with the existence of granular superconductivity, similar to that found also in thin mesoscopic graphite samples. Springer Science+Business Media, LLC, 2010 Andreev oscillations nationallicence Normal-superconducting nanostructures nationallicence Granular superconductivity nationallicence Focused ion beam nationallicence Barzola-Quiquia J. Division of Superconductivity and Magnetism, University of Leipzig, 04013, Leipzig, Germany aut Dusari S. Division of Superconductivity and Magnetism, University of Leipzig, 04013, Leipzig, Germany aut Chiliotte C. Division of Superconductivity and Magnetism, University of Leipzig, 04013, Leipzig, Germany aut Esquinazi P. Division of Superconductivity and Magnetism, University of Leipzig, 04013, Leipzig, Germany aut Journal of Superconductivity and Novel Magnetism Springer US; http://www.springer-ny.com 24/1-2(2011-01-01), 463-469 1557-1939 24:1-2<463 2011 24 10948 https://doi.org/10.1007/s10948-010-0973-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10948-010-0973-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Barzola-Quiquia J. Division of Superconductivity and Magnetism, University of Leipzig, 04013, Leipzig, Germany aut NATIONALLICENCE 700 1- Dusari S. Division of Superconductivity and Magnetism, University of Leipzig, 04013, Leipzig, Germany aut NATIONALLICENCE 700 1- Chiliotte C. Division of Superconductivity and Magnetism, University of Leipzig, 04013, Leipzig, Germany aut NATIONALLICENCE 700 1- Esquinazi P. Division of Superconductivity and Magnetism, University of Leipzig, 04013, Leipzig, Germany aut NATIONALLICENCE 773 0- Journal of Superconductivity and Novel Magnetism Springer US; http://www.springer-ny.com 24/1-2(2011-01-01), 463-469 1557-1939 24:1-2<463 2011 24 10948 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer