1. Department of Materials Science & Engineering , Massachusetts Institute of Technology , Cambridge 02139 , MA , USA
2. Department of Electrical & Computer Engineering , University of Massachusetts Lowell , Lowell 01854 , MA , USA
3. Booz Allen Hamilton Inc , Arlington 22203 , VA , USA
4. Department of Physics , University of Cambridge , Cambridge CB3 0HE , UK
5. Materials Research Laboratory , Massachusetts Institute of Technology , Cambridge 02139 , MA , USA
6. NASA Langley Research Center , Hampton 23681-2199 , VA , USA