1. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
2. Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, South Korea
3. Department of Physics and Astronomy, Seoul National University, Seoul 08826, South Korea
4. School of Materials Science and Engineering, Chonnam National University, Gwangju 61186, South Korea
5. Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
6. Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA