1. Center for Condensed Matter Sciences National Taiwan University Taipei 10617 Taiwan
2. Institute of Physics Academia Sinica Taipei 11529 Taiwan
3. Department of Mechanical Engineering Chung Yuan Christian University Taoyuan 32023 Taiwan
4. Department of Materials Science and Engineering University of California Berkeley CA 94720 USA
5. Lawrence Berkeley National LaboratoryMaterials Sciences Division Berkeley CA 94720 USA
6. Aston Institute of Photonic Technologies Aston University Birmingham B4 7ET UK
7. Taiwan Consortium of Emergent Crystalline Materials Ministry of Science and Technology Taipei 10622 Taiwan
8. Center of Atomic Initiative for New Materials National Taiwan University Taipei 10617 Taiwan