1. Department of Applied and Engineering Physics, Cornell University , Ithaca, NY , USA
2. Department of Materials Science and Engineering, Cornell University , Ithaca, NY , USA
3. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, CA , USA
4. Department of Applied Physics, Stanford University , Stanford, CA , USA
5. Department of Physics, Stanford University , Stanford, CA , USA
6. Advanced Photon Source, Argonne National Laboratory , Lemont, IL , USA
7. Max Planck Institute for Chemical Physics of Solids , Dresden , Germany
8. Kavli Institute at Cornell for Nanoscale Science, Cornell University , Ithaca, NY , USA