**Author details**

Heike C. Herper<sup>1</sup> , Barbara Brena<sup>1</sup> , Sumanta Bhandary<sup>2</sup> and Biplab Sanyal<sup>1</sup> \*

\*Address all correspondence to: Biplab.Sanyal@physics.uu.se

1 Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden

2 Institute of Solid State Physics, TU Wien, Wien, Austria
