1. Materials Science Department, University of Patras, 26504 Patras, Greece
2. Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, and School of Materials Science and Engineering, Henan University, Kaifeng, Henan 475001, China
3. Physical Chemistry and Physics Departments, University of Hamburg, HARBOR build., Luruper Chaussee 149, D-22761 Hamburg, Germany
4. Department of General Physics and Quantum Nanostructures, Russian-Armenian University, Yerevan 0051, Armenia