1. School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA
2. Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, PL-01-142 Warsaw, Poland
3. Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
4. Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA