1. Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada N2L 3G1
2. Stanford Institute for Materials and Energy Science, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA
3. Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA
4. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
5. Department of Physics, Stanford University, Stanford, CA 94305, USA
6. Department of Physics and Astrophysics, University of North Dakota, Grand Forks, ND 58202, USA
7. Department of Applied Physics, Stanford University, Stanford, CA 94305, USA