1. School of Chemistry and Physics Westville Campus University of KwaZulu-Natal 1 University Rd Chiltern Heights Westville Durban 4000 South Africa
2. Institute of Physics Academia Sinica Taipei 11529 Taiwan
3. Nanosciences African Network (NANOAFNET), iThemba LABS National Research Foundation of South Africa 1 Old Faure Road Western Cape 7129 South Africa
4. Institute of Solid-State Physics Friedrich Schiller University 07743 Jena Germany
5. Department of Physics TUCACS Campus Thennangur Thiruvalluvar University Vellore Tamil Nadu India
6. Physics Department University of Free State Bloemfontein 9300 South Africa
7. Microscopy and Microanalysis Unit School of Life Sciences University of KwaZulu-Natal Durban 4000 South Africa