1. Department of Physics and Energy Harvest Storage Research Center, University of Ulsan, Ulsan 44610, South Korea
2. School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, South Korea
3. Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
4. Center for Scientific Instrumentation, Division of Scientific Instrumentation and Management, Korea Basic Science Institute, Daejeon 34133, South Korea
5. Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea