Fuchs, F.
Stender, B.
Trupke, M.
Simin, D.
Pflaum, J.
Dyakonov, V.
Astakhov, G. V.
Article History
Received: 4 August 2014
Accepted: 19 May 2015
First Online: 7 July 2015
Competing interests
: The authors declare no competing financial interests.