Cao Thi My Dung (Faculty of Materials Science, University of Science, Vietnam National University), Nhu Hoa Tran Thi (Faculty of Materials Science, University of Science, Vietnam National University), Kieu Hanh Thi Ta (Faculty of Materials Science, University of Science, Vietnam National University), Vinh Cao Tran (Laboratory of Advanced Materials, University of Science, Vietnam National University), Bao Thu Le Nguyen (Department of Mathematics and Physics, University of Information Technology, Vietnam National University), Van Hieu Le (Faculty of Materials Science, University of Science, Vietnam National University), Phuong Anh Do (Department of Solid State Physics, Faculty of Physics, Hue University), Anh Tuan Dang (Department of Solid State Physics, Faculty of Physics, Hue University), Heongkyu Ju (Department of Nano-Physics, Gachon University), Bach Thang Phan * (Faculty of Materials Science, University of Science, Vietnam National University)