1. Center for Nanophysics and Advanced Materials, and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States
2. Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 46241, Republic of Korea
3. Crystal Bank Research Institute, Pusan National University, Miryang 50463, Republic of Korea
4. Analytical Engineering Group, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Suwon 16678, Republic of Korea
5. Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
6. Department of Nanoenergy Engineering, Pusan National University, Busan 46241, Republic of Korea
7. Department of Optics and Mechatronics Engineering, Pusan National University, Busan 46241, Republic of Korea
8. Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon 16419, Republic of Korea