Seradjeh B, Moore J E, Franz M
Department of Physics, University of Illinois, Urbana, Illinois 61801-3080, USA.
Phys Rev Lett. 2009 Aug 7;103(6):066402. doi: 10.1103/PhysRevLett.103.066402.
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 novel exotic quantum state which we propose to call "topological exciton condensate" (TEC). This TEC is similar in general terms to the exciton condensate recently argued to exist in a biased graphene bilayer, but with different topological properties. It exhibits a host of unusual properties including a stable zero mode and a fractional charge +/-e/2 carried by a singly quantized vortex in the TEC order parameter.
强拓扑绝缘体表面必定存在奇数个无隙狄拉克费米子。我们表明，在薄膜几何结构和外部偏压下，处于这些表面态的电子 - 空穴对能够凝聚形成一种新型奇异量子态，我们提议将其称为“拓扑激子凝聚态”（TEC）。这种TEC总体上类似于最近有人认为存在于有偏压的双层石墨烯中的激子凝聚态，但具有不同的拓扑性质。它展现出许多不寻常的特性，包括一个稳定的零模以及TEC序参量中单个量子化涡旋所携带的分数电荷±e/2。
