Berlin 2018 – scientific programme

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PLV: Plenarvorträge

PLV II

PLV II: Plenary Talk

Monday, March 12, 2018, 08:30–09:15, H 0105

Imaging Topological Electrons in Low Dimensions: from the Inorganic to the Organic — •Michael F. Crommie — UC Berkeley Physics Dept., Berkeley, CA, USA — Lawrence Berkeley National Laboratory, Materials Sciences Division, Berkeley, CA, USA

The idea of classifying materials by their topological properties is useful for predicting their behavior, especially at interfaces. Materials belonging to different topological classes exhibit conducting states at the interfaces between them, even when the materials are insulators to begin with. But what do these topologically-protected electrons look like? Somewhat ironically, electrons in low-dimensional topological systems (such as 1D molecular chains and 2D quantum wells) that have long been studied are quite difficult to image, whereas newer 3D topological systems are much more accessible to imaging via scanning tunneling microscopy (STM). I will discuss recent developments that have resulted in new low-dimensional topological systems that are increasingly accessible to microscopists who image electrons. The first is a 2D class of inorganic material, the transition metal dichalcogenides (TMDs). Single TMD layers in the 1T(prime) phase are 2D topological insulators. I will discuss our recent efforts to image electrons that inhabit topologically protected edge-states in this new quantum spin Hall insulator. The second system is molecular: graphene nanoribbons are 1D topological insulators. I will discuss our recent efforts to engineer the topological properties of this organic system, and to image resulting electronic behavior at sub-nm lengthscales.