1. Department of Applied Physics, Osaka University, 2-1 Yamadaoka,
Suita, Osaka 565-0871, Japan
2. CCMS, Institute of Physics, Slovak Academy of Sciences, 84511 Bratislava, Slovakia
3. Faculty of Electrical Engineering and Information Technology, Slovak University of Technology in Bratislava, 812 19 Bratislava, Slovakia
4. Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China, Taiyuan, Shanxi 030051, China
5. Low-Dimensional and Surface Physics, Department of Physics, Renmin University of China, LiGongLou 714, Beijing 100872, P. R. China
6. Institute for Interdisciplinary Research, Jianghan University, Wuhan 430056, China
7. Department of Physics, School of Natural and Mathematical Sciences, King’s College London, The Strand, London WC2R 2LS, U.K.
8. Institute of Informatics, Slovak Academy of Sciences, 845 07 Bratislava, Slovakia
9. Department of Natural Sciences, University of Ss. Cyril and Methodius, 917 01 Trnava, Slovakia