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SUMMARY:Non-Perturbative Effects in Disordered Topological Insulators - Zo
 har Ringel\, Weizmann Institute of Science
DTSTART:20130208T153000Z
DTEND:20130208T163000Z
UID:TALK43286@talks.cam.ac.uk
CONTACT:Gareth Conduit
DESCRIPTION:Disorder and topology can be thought of as two counter-driving
  forces. While the former pushes electron wave functions to localize in sp
 ace\, the latter requires them to remain coherent over the entire system. 
 We study the interplay between these two on the surface of a "weakly" topo
 logical phase -- the Weak Topological Insulator. Using arguments based on 
 flux-insertions and locality\, we show that such surfaces cannot undergo a
  localization transition even when the surface is strongly disordered. We 
 then reformulate the same notions\, in field theory language\, using a nov
 el Z_2-charge-anomaly. This anomaly generalizes the Z-charge-anomaly assoc
 iated with edges of the Integer Quantum Hall Effect. Besides unifying vari
 ous aspects of Topological Insulators\, the anomaly allows us to calculate
  new topological properties of TIs in the presence of electric fields.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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