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arXiv · 0902.1147

Exciton condensation and charge fractionalization in a topological insulator film

B. Seradjeh·J. E. Moore·M. Franz
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Abstract

An odd number of gapless Dirac fermions is guaranteed to exist at a surface of a strong topological insulator. We show that in a thin-film geometry and under external bias, electron-hole pairs that reside in these surface states can condense to form a coherent exciton condensate, similar in general terms to the exciton condensate recently argued to exist in a biased graphene bilayer, but with different topological properties. Such a `topological' exciton condensate (TEC) exhibits a host of unusual properties; the most interesting among them is the fractional charge +-e/2 carried by a singly quantized vortex in the TEC order parameter.

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B. Seradjeh, J. E. Moore, M. Franz. 2009-07-16. Exciton condensation and charge fractionalization in a topological insulator film. https://doi.org/10.1103/physrevlett.103.066402

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