1. Institute of Physics, National Academy of Sciences, 03650 Kyiv, Ukraine
2. Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
3. Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio 45433, USA
4. Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, USA
5. Physics Department, Uzhgorod National University, 88000 Uzhgorod, Ukraine