1. Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Republic of Singapore.
2. Institute of Materials, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
3. Singapore Eye Research Institute, Singapore 169856, Republic of Singapore.
4. Hysitron Inc., 10025 Valley Road, Minneapolis, MN 55344, USA.
5. Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology, and Research), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore.
6. Western Digital Company, Recording Sub System Staging and Research, San Jose, CA 95135, USA.
7. Center for Nanoscale Materials, Argonne National Laboratory, 9700 S Cass Avenue, Argonne, IL 60439, USA.