1. Graduate School of Engineering Science, Osaka University 1 , Toyonaka, Osaka 560-8531, Japan
2. Spintronics Research Network Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University 2 , Suita, Osaka 565-0871, Japan
3. Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University 3 , Toyonaka, Osaka 560-8531, Japan
4. Division of Nanotechnology, Daegu Gyeongbuk Institute of Science and Technology (DGIST) 4 , Daegu 42988, South Korea
5. Department of Physics and Chemistry, Daegu Gyeongbuk Institute of Science and Technology (DGIST) 5 , Daegu 42988, South Korea
6. ULVAC-Osaka University Joint Research Laboratory for Future Technology, Osaka University 6 , Suita, Osaka 565-0871, Japan