1. Department of Mathematical, Physical and Computer Sciences, University of Parma, Viale delle Scienze 7/A, 43124 Parma, Italy
2. Institute of Materials for Electronics and Magnetism (IMEM-CNR), Viale delle Scienze 37/A, 43124 Parma, Italy
3. Institute for Microelectronics and Microsystems, CNR-IMM Agrate Unit, Via Camillo Olivetti 2, 20864 Agrate Brianza (MB), Italy