1. Materials Research and Education CenterDepartment of Mechanical EngineeringAuburn University Auburn Alabama 36849 USA
2. Department of PhysicsStony Brook University Stony Brook NY 11794 USA
3. Department of PhysicsMassachusetts Institute of Technology Cambridge MA 02215 USA
4. Department of Materials Science and EngineeringUniversity of Virginia Charlottesville VA 22904 USA
5. Department of PhysicsFaculty of ScienceChulalongkorn University Bangkok 10330 Thailand
6. Department of PhysicsColumbia University New York NY 10027 USA
7. National Institute for Materials Science Namiki 1‐1 Tsukuba Ibaraki 305‐0044 Japan
8. Division of NanophotonicsCAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology Beijing 100190 P. R. China