1. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
2. Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
3. Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA.
4. Department of Physics and Astronomy, Clemson University, Clemson, SC 29631, USA.
5. Department of Physics, Stanford University, Stanford, CA 94305, USA.
6. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
7. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
8. Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.