1. National Nanotechnology Laboratory of Istituto Nanoscienze‐CNR Via Arnesano I‐73100 Lecce Italy
2. Department of Materials Science and Engineering Frederick Seitz Materials Research Laboratory, and Beckman Institute for Advanced Science University of Illinois at Urbana‐Champaign Urbana IL 61801 USA
3. Dipartimento di Ingegneria dell'Innovazione Università del Salento Via Arnesano I‐73100 Lecce Italy
4. Institut für Angewandte Mechanik Technische Universität Braunschweig Bienroder Weg 87 Campus Nord D‐38106 Braunschweig Germany
5. Dipartimento di Matematica e Fisica “Ennio De Giorgi” Università del Salento Via Arnesano I‐73100 Lecce Italy