1. Department
of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, United States
2. Department
of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States
3. Electron
Microscope Facility, Clemson Research Park, Clemson University, Clemson, South Carolina 29634, United States
4. King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia