1. Department of Physics and Chemistry, Daegu Gyeongbuk Institute of Science and Technology (DGIST) 1 , Daegu 42988, Republic of Korea
2. Quantum Spin Team, Korea Research Institute of Standards and Science (KRISS) 2 , Daejeon 34113, Republic of Korea
3. Department of Physics, Kunsan National University 3 , Kunsan 54150, Republic of Korea