1Department of Physics, University of Rajshahi, Rajshahi, Bangladesh
2Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, Somerset West, South Africa
3UNESCO-UNISA Africa Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Pretoria, South Africa
4Department of Medical Physics, Khwaja Yunus Ali University , Sirajgonj, Bangladesh
5Council for Scientific and Industrial Research, Pretoria, South Africa
6Department of Physics, Florida A & M University, Tallahassee, FL, USA