1. ULVAC-Osaka University Joint Research Laboratory for Future Technology, Osaka University, 2-1, Yamadaoka, Suita, Osaka 560-0871, Japan
2. Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
3. Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan