1. Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, United States; Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, United States; NSF Center for Micro-Engineered Materials, Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131, United States; and Center for Composite Materials, University of Delaware, Newark, Delaware 19716, United States