1. Department of Physics, National Changhua University of Education, Changhua 500, Taiwan
2. Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan
3. Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
4. Russian Quantum Center, Skolkovo, 143025 Moscow, Russia
5. Prokhorov General Physics Institute, RAS, 119991 Moscow, Russia
6. Department of Physics, National Cheng Kung University, Tainan 701, Taiwan