1. Adelwitz Technologiezentrum GmbH (ATZ) 1 , Naundorfer Str. 29, D-04860 Torgau, Germany
2. Department of Physics and Texas Center for Superconductivity at the University of Houston (TcSUH), University of Houston 2 , Houston, Texas 77204, USA
3. Leibniz Institute for Solid State and Materials Research 3 , Dresden, Germany