1. Department of Physics, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
2. Graduate School of Science, Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
3. Center for Spintronics Research Network, Osaka University, Toyonaka, Osaka 560-8531, Japan
4. Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris Saclay, 91405 Orsay Cedex, France
5. Institute for Physics of Intelligence and Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
6. Graduate School of Science and CSIS, Tohoku University, Sendai 980-8578, Japan