1. Department
of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San
Juan 00936, Puerto Rico, United States
2. Department
of Mechanical Engineering,College of Engineering, University of Texas, El Paso, Texas 79968, United States
3. Department
of Physics, Indian Institute of Technology, Kharagpur 721302, India
4. Department
of Physics, National Institute of Technology, Rourkela 769008, India
5. Department
of Chemistry and Department of Physics, University of St. Andrews, St.
Andrews KY16 ST, United Kingdom