CMT Seminar - Monday, January 30th - Babak Seradjeh, Indiana University

[Longbrake, Patricia]

Good afternoon,

Please join us for the CMT Seminar on Monday, January 30th presented by Babak Seradjeh, Indiana University.  The talk will take place in the Smith Seminar Room at 11:30am.  The title and abstract for the talk are listed below.

Please contact me as soon as possible if you would like to meet with Dr. Seradjeh.  I still have a small number of spaces available on his schedule.

TITLE:  Topological Exciton Condensate

ABSTRACT:  Recent advances in the study of band insulators have revealed the existence of new topological invariants that characterize these materials. Among the three-dimensional time-reversal invariant insulators a "strong" topological insulator (STI) was predicted to exist, shortly followed by experimental confirmations in several Bi-related materials with strong spin-orbit interaction. The STI is characterized physically by gapless surface states with an odd number of Fermi level crossing pairs, which remain metallic even in the presence of disorder. These states exhibit linear dispersion and behave as massless Dirac fermions familiar from the physics of graphene. Having an odd number of Dirac fermions leads to some exotic properties associated with surfaces of a STI, such as fractional quantum Hall conductivity.
We have recently predicted that a "topological exciton condensate" is spontaneously formed by the Coulomb interaction in the thin-film geometry, which intriguingly supports vortices with a precisely fractional value of charge, e/2. This is a distinct correlated phase of matter enabled by the special properties of topological insulators. I shall review these developments and their background, present our theory of the topological exciton condensate, examine the effects of external magnetic field and particle-hole imbalance, and conclude by discussing the promise for experimental observation of this state.

Thank you,
Trisch
2-2778
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