1. Department of Physics ‘E.R. Caianiello’, University of Salerno, Via Giovanni Paolo II 132, Fisciano 84084, Italy
2. CNR-SPIN Salerno, Via Giovanni Paolo II 132, Fisciano 84084, Italy
3. Department of Science and Technology, University of Sannio, Via de Sanctis, Benevento 82100, Italy
4. Fakultät für Physik and CENIDE, Universität Duisburg-Essen, Lotharstrasse 1, Duisburg D-47057, Germany
5. Narrando Srl, Via Arcangelo Rotunno 43, Salerno 84134, Italy