Topology vs. interaction in fragile bands
- đ¤ Speaker: Ady Stern, Weizmann Institute of Science
- đ Date & Time: Thursday 29 April 2021, 14:00 - 15:00
- đ Venue: Details of video conferencing will be distributed nearer the time.
Abstract
Topological systems of non-interacting electrons may be forced by their topological nature to have a gapless spectrum. As two examples, Integer quantum Hall states and topological insulators must carry gapless edge states, which allow them to carry current. Whether interaction between the electrons may turn a gapless conductor into a fully gapped insulator depends on the case at hand, with a negative answer for the first example and a positive for the second.
In this talk I will review these two examples, and then focus on bands of fragile topology. I will explain what fragile topology is as well as how and when it forbids a gapped spectrum at the non-interacting level. Then, I will show that interactions may be powerful enough to overcome the decree issued by topology, and explain how they do that. Finally, I will discuss relevance to twisted bi-layers of graphene.
Series This talk is part of the Theory of Condensed Matter series.
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Ady Stern, Weizmann Institute of Science
Thursday 29 April 2021, 14:00-15:00