1. Department of Physics and Center for Functional Materials, Wake Forest University, Winston Salem, North Carolina 27109, United States
2. Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
3. Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, United States
4. Department of Physics and Astronomy, Appalachian State University, Boone, North Carolina 28608, United States