1. Departments of Applied Physics and Physics, Stanford University, Stanford, CA 94305, USA.
2. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.
3. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
4. National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan.
5. Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
6. Institute Lorentz for Theoretical Physics, Leiden University, 2300 RA Leiden, Netherlands.