1. Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
2. School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, South Korea
3. King Abdullah University of Science and Technology (KAUST), Imaging and Characterization core laboratory, Thuwal 23955-6900, Saudi Arabia
4. Physics Department, Faculty of Science, Taif University, 21974 Taif, P. O. Box 888, Saudi Arabia
5. King Abdullah University of Science and Technology (KAUST), Computer Electrical Mathematical Science and Engineering, Thuwal 23955-6900, Saudi Arabia