1. Department
of Energy Science, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
2. Center
for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
3. Department
of Nano Applied Engineering, Kangwon National University, Chuncheon 24341, Republic of Korea
4. Department of Physics & Astronomy and Center for Computational Sciences, Mississippi State University, Starkville, Mississippi 39762, United States
5. Department
of Physics, Kunsan National University, Gunsan 54150, Republic of Korea