1. National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania
2. Faculty of Physics, University of Bucharest, 405 Atomistilor Street, 077125 Magurele, Romania
3. National Institute for Research and Development in Optoelectronics, 409 Atomistilor Street, 077125 Magurele, Romania
4. National Institute for Research and Development in Microtechnologies, 077190 Voluntari, Romania
5. Peter Grünberg Institut 9 (PGI 9) and JARA Fundamentals of Future Information Technologies, Forschungszentrum Jülich, 52425 Jülich, Germany
6. Academy of Romanian Scientists, Bucharest, 050094 Bucharest, Romania