1. Faculty of Chemistry and Food Chemistry; Technische Universität Dresden; 01062 Dresden Germany
2. Institute of Solid State and Materials Physics; Technische Universität Dresden; 01062 Dresden Germany
3. Leibniz Institute for Solid State and Materials Research Dresden; IFW Dresden; 01171 Dresden Germany
4. Departamento de Física Teórica e Experimental (DFTE); Universidade Federal do Rio Grande do Norte; 59078-970 Natal-RN Brazil