1. CNR‐IOM TASC Laboratory Area Science Park‐Basovizza Trieste 34139 Italy
2. Department of Physics Indian Institute of Technology Kanpur Kanpur 208016 India
3. State Key Laboratory for Infrared Physics Shanghai Institute of Technical Physics Chinese Academy of Sciences 500 Yu‐tian Road Shanghai 200083 China
4. Department of Optoelectronic Science and Engineering Donghua University Shanghai 201620 China
5. College of Science Institute of Materials Physics and Chemistry Nanjing Forestry University Nanjing 210037 P. R. China
6. Theoretical Physics and Applied Mathematics Department Ural Federal University Mira Street 19 Ekaterinburg 620002 Russia
7. Department of Surface and Plasma Science Prague Charles University V Holesovickaˇch 2, Prague 8 Prague 18000 Czech Republic
8. Department of Physics National Cheng Kung University 1 Ta‐Hsueh Road Tainan 70101 Taiwan
9. Taiwan Consortium of Emergent Crystalline Materials Ministry of Science and Technology Taipei 10601 Taiwan
10. INSTM and Department of Physical and Chemical Sciences University of L'Aquila via Vetoio L'Aquila AQ 67100 Italy
11. CNR‐IMM Istituto per la Microelettronica e Microsistemi VIII strada 5 Catania I‐95121 Italy