1. CNR-SPIN
Institute
for Superconductors, Innovative Materials, and Devices, C.so Perrone 24, 16152 Genova, Italy
2. CNR-SPIN and Physics Department, University of Naples Federico II, Piazzale Tecchio, 80125 Napoli, Italy
3. Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany