1. Nanotechnology and Functional Materials Department of Materials Science and Engineering The Ångström Laboratory Uppsala University Uppsala 751 21 Sweden
2. Solid State Physics Department of Materials Science and Engineering The Ångström Laboratory Uppsala University Uppsala 751 21 Sweden
3. College of Materials Science and Engineering Hunan University Changsha Hunan 410082 China
4. Department of Chemistry‐Ångström Uppsala University Uppsala 751 21 Sweden