1. Department of Materials Science and Engineering and Research Institute of Advanced Materials; Seoul National University; Seoul 151-742 South Korea
2. Research and Development Center; Samsung Display; Yongin 446-711 South Korea
3. Department of Materials Science and Engineering; Inha University; Incheon 402-751 South Korea
4. Center for Correlated Electron Systems; Institute for Basic Science (IBS); Seoul 151-747 South Korea
5. Department of Physics and Astronomy; Seoul National University; Seoul 151-747 South Korea