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SUMMARY:Topology vs. interaction in fragile bands - Ady Stern\, Weizmann I
 nstitute of Science
DTSTART:20210429T130000Z
DTEND:20210429T140000Z
UID:TALK157579@talks.cam.ac.uk
CONTACT:Jan Behrends
DESCRIPTION: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 betw
 een the electrons may turn a gapless conductor into a fully gapped insulat
 or depends on the case at hand\, with a negative answer for the first exam
 ple and a positive for the second.\n\nIn this talk I will review these two
  examples\, and then focus on bands of fragile topology. I will explain wh
 at fragile topology is as well as how and when it forbids a gapped spectru
 m at the non-interacting level. Then\, I will show that interactions may b
 e 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.
LOCATION:Details of video conferencing will be distributed nearer the time
 .
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