1. a Department of Physics, College of Natural Sciences, Hanoi National University, No. 334, Nguyen Trai Str., Thanh Xuan Dist., Hanoi, Vietnam;, Email: nguyenquangbau54@gmail.com
2. b Department of Physics, College of Natural Sciences, Hanoi National University, No. 334, Nguyen Trai Str., Thanh Xuan Dist., Hanoi, Vietnam
3. c Department of Physics, College of Natural Sciences, Hanoi National University, No. 334, Nguyen Trai Str., Thanh Xuan Dist., Hanoi, Vietnam