1. Georg‐August University of Göttingen Institute for Materials Physics Friedrich‐Hund Platz 1 37077 Göttingen Germany
2. Institute of Electronic Engineering and Nanotechnologies Academiei str., 3/3 Chisinau MD‐2028 Republic of Moldova
3. Georg‐August University of Göttingen I. Institute of Physics Friedrich‐Hund Platz 1 37077 Göttingen Germany