1. Department of Mechanical Engineering & Material Science, Washington University in St. Louis, Missouri 63130 and Institute of Materials Science & Engineering, Washington University in St. Louis, Missouri 63130
2. Department of Mechanical Engineering & Material Science, Washington University in St. Louis, Missouri 63130
3. Department of Physics, Washington University in St. Louis, Missouri 63130
4. SAFC Hitech, 1429 Hilldale Ave., Haverhill, Massachusetts 01832
5. Institute of Materials Science & Engineering, Washington University in St. Louis, Missouri 63130 and Department of Physics, Washington University in St. Louis, Missouri 63130