1. Central European Institute of Technology, Brno University of Technology, 612 00 Brno, Czech Republic
2. Institute of Physical Engineering, Faculty of Mechanical Engineering, Brno University of Technology, 616 69 Brno, Czech Republic
3. Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maxilimians-Universität München, 80539 München, Germany
4. Departmento de Física, Universidade Federal de Pernambuco, 50670-901 Recife-PE, Brazil
5. Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom