Markus Scholz received Ph. D. with "summa cum laude"
This photo shows to the right Markus Scholz with the president of the examination committee, Prof. Matias Bargheer, after the successful defense. © Rader, HZB
These materials are insulators which display metallic conductivity at their surface. The topological aspects lead to a protection of the metallic states towards distortions of the system and permit, in principle, a dissipationless transport of current. Hence, topological insulators play a prominent role in approaches for realizing a "green" information technology.
The spectroscopic methods available at BESSY II are very well suited for studying these conducting states, in particular spin-resolving spectroscopies and circular dichroism, a key activity of the group. Prior to Markus Scholz' investigations, it had been believed that the presence of magnetic moments, which break time-reversal symmetry, destroy the topological surface state at its point of degeneracy (Dirac point), i. e., forms a band gap there. This was disproved by Markus Scholz' careful experimental work. He demonstrated the robustness of the surface states and how their lifetime broadening is influence by the magnetic moments.
Markus Scholz is currently continuing his research as postdoc at Würzburg University.