1. Nanomaterials Research Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
2. Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
3. Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
4. Fraunhofer-Institute for Applied Solid State Physics (IAF), Tullastraße 72, Freiburg 79108, Germany