1. Institute of Physics (IA), RWTH Aachen University, Aachen 52056, Germany
2. DWI Leibniz-Institute for Interactive Materials, Aachen 52074, Germany
3. U.S. Naval Research Laboratory, Washington, D.C., United States
4. NRC Postdoctoral Fellow (Residing at US. Naval Research Laboratory, Washington, D.C., United States
5. Departamento de Matemática-Física, Universidad de Puerto Rico−Cayey, Cayey 00736, Puerto Rico
6. Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37205 United States