1. Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, D-01328 Dresden, Germany
2. Technische Universität Dresden, D-01062 Dresden, Germany
3. Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
4. Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan