1. M. Fiebig, Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan, and Japan Science and Technology Corporation (JST), Tokyo 171-0031, Japan.
2. K. Miyano, Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan.
3. Y. Tomioka, Joint Research Center for Atomic Technology (JRCAT), Tsukuba 305-0046, Japan.
4. Y. Tokura, Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan, and JRCAT, Tsukuba 305-0046, Japan.