1. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
2. Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
3. Department of Physics, Tamkang University, New Taipei City 25137, Taiwan
4. Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany
5. Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 10617, Taiwan
6. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan