Strong and Weak Topology Probed by Surface Science

Topological Insulator Properties of Phase Change Alloys and Heavy Metal Graphene

  • Christian┬áPauly

Part of the MatWerk book series (MW)

Table of contents

  1. Front Matter
    Pages I-VIII
  2. Christian Pauly
    Pages 1-4
  3. Christian Pauly
    Pages 5-40
  4. Christian Pauly
    Pages 41-57
  5. Christian Pauly
    Pages 105-142
  6. Christian Pauly
    Pages 143-144
  7. Back Matter
    Pages 145-166

About this book


Christian Pauly demonstrates the strong topological properties of the technologically relevant phase change materials Sb2Te3 and Ge2Sb2Te5 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 Bi14Rh3I9, 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.



  • Fundamentals of topological insulators
  • Experimental methods
  • Identification of tellurium based phase change materials as strong topological insulators
  • Weak topological insulators


Target Groups

  • Researchers and students from the fields of
physics, especially condensed materials


About the Author

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.


scanning tunneling microscopy STM angle-resolved photoemission spectroscopy ARPES weak topological insulator atomic scale mapping phase change material

Authors and affiliations

  • Christian┬áPauly
    • 1
  1. 1.2nd Physical Institute BRWTH Aachen UniversityAachenGermany

Bibliographic information