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Twisting and Stretching van der Waals Bilayers: an Atomic-Scale View

Abhay Pashupathy, Columbia University
Monday, March 11, 2019 - 4:00pm to 5:00pm
PAA 102

With the magic of scotch tape, it has now become possible to create artificial layered materials with unique electronic properties. An example of this is a twisted bilayer, where two single layer sheets of a layered material can be stacked together to create a bilayer, but with a controllable twist between the layers. Such structures have new single-electron and many body properties that each of the individual layers may not exhibit. I will discuss two such materials in this talk. The first of these is twisted bilayer graphene, a material which displays interesting new electronic phases including insulating behavior, superconductivity and magnetism. I will discuss scanning tunneling microscopy measurements of this material from my laboratory where we can visualize the atomic structure and measure the excitations of this unique material. The second material I will discuss is heterostrained transition metal dichalcogenides. I will show that strain applied to one layer relative to the other can create new atomic structures termed "strain solitons". I will discuss the formation, manipulation and electronic properties of these solitons. 

Watch a video of the talk here.

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