1. Chair of Inorganic Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany
2. Department of Physics, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany
3. Wuppertal Center for Smart Materials & Systems, University of Wuppertal, 42119 Wuppertal, Germany