1. Department of Physics “E. Pancini”, University of Naples Federico II, Via Cintia 26, 80126Naples, Italy
2. INESC─Microsistemas e Nanotecnologias, Lisboa, Rua Alves Redol 9, 1000-049Lisbon, Portugal
3. Department of Chemistry, University of Naples Federico II, Via Cintia 26, 80126Naples, Italy
4. Instituto Superior Tecnico (IST), Universidade de Lisboa, Av. Rovisco Pais, 1649-004Lisboa, Portugal
5. CNR─SPIN (Institute for Superconductors, Oxides and Other Innovative Materials and Devices), Piazzale V. Tecchio 80, 80125Naples, Italy