Gapless topological states in bilayer graphene

Date: 20 February 2018

Venue: University of Antwerp - Campus Groenenborger - Room U.244 - Groeneborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger)

Time: 4:00 PM - 5:00 PM

Organization / co-organization: Condensed Matter Theory

Short description: Condensed Matter Theory seminar presented by Miša Anđelković

Theoretically predicted, and experimentally confirmed gap opening of AB (also known as Bernal) stacked bilayer graphene in perpendicular electric field was a significant achievement on the road to making a graphene transistor. But only the highest quality samples appeared to be fully gapped. It was later shown that boundaries between different stacking domains host a group of topologically protected ballistic electron channels. Surprisingly enough, stacking faults as an unwanted phenomenon that caused the occurrence of in-gap states in gated graphene bilayers, led to novel transport opportunities for 2D materials.

In this talk we will discuss about the appearance of such electronic states at the domain walls, and even grain boundaries, being examples of structural disorder, and in double gated structures where they appear induced by the kink potential. We will show some approaches for their manipulation and possibilities for application. Properties like valley dependent behaviour and no-valley mixing gives us the opportunity to explore them for valleytronics applications. Also, recent theoretical predictions showed that layer polarization can be manipulated by changing the gap size and tuning the Fermi energy. The possibility to control different degrees of freedom could appear to be significant achievement for novel transport devices.The final goal of the talk would be to show both theoretical and experimental advancements in the field.

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