Quantum Spin Team, Korea Research Institute of Standards and Science, Quantum Spin Team, Korea Research Institute of Standards and Science, Nanoscale Semiconductor Engineering, Department of Physics, Hanyang University, Quantum Spin Team, Korea Research Institute of Standards and Science, Quantum Spin Team, Korea Research Institute of Standards and Science, Quantum Spin Team, Korea Research Institute of Standards and Science, Nanoscale Semiconductor Engineering, Department of Physics, Hanyang University, Korea Research Institute of Standards and Science (KRISS) - Quantum Spin Team and Hanyang University - Nanoscale Semiconductor Engineering