Christian Pauly demonstrates the strong topological properties of the technologically relevant phase change materials Sb 2 Te 3 and Ge 2 Sb 2 Te 5 by using two powerful techniques for mapping the surface electronic structure: scanning tunneling spectroscopy (STS) and angle-resolved photoemission spectroscopy (ARPES). In the case of a phase change material, this opens up the possibility of switching between an insulating amorphous and a conducting topological phase on nanosecond-time scales. Moreover, the author presents first experimental results of a weak topological insulator, namely on the bismuth-based graphene-like sheet system Bi 14 Rh 3 I 9 , revealing a topologically protected one-dimensional edge channel as its fingerprint. The edge state is as narrow as 0.8 nm, making it extremely attractive to device physics. Those strong and weak topological insulators are a new phase of quantum matter giving rise to robust boundary states which are protected from backscattering and localization.

Publication in the field of natural sciences

Autorentext

Christian Pauly is working as a postdoc in the II. Institute of physics B of the RWTH Aachen University. His work focuses on the study of the topological properties of graphene-like sheet systems which belong to the class of weak topological insulators.

Inhalt
Introduction.- Fundamentals of Topological Insulators.- Experimental Methods.- Identication of Tellurium based Phase-Change Materials as Strong Topological Insulators.- Weak Topological Insulator.- Summary.