2005/08/31 by Congjun Wu, B. Andrei Bernevig, Shou-Cheng Zhang · 2 citations
Physics and Astronomy · #cond-mat.other
paper · pdf · doi:10.1103/physrevlett.96.106401
published as Phys. Rev. Lett. 96, 106401 (2006) · 4 pages, accepted by Phys. Rev. Lett
arxiv created 2006/02/27 · arxiv updated 2009/12/01
The edge states of the recently proposed quantum spin Hall systems constitute a new symmetry class of one-dimensional liquids dubbed the ``helical liquid'', where the spin orientation is determined by the direction of electron motion. We prove a no-go theorem which states that a helical liquid with an odd number of components cannot be constructed in a purely 1D lattice system. In a helical liquid with an odd number of components, a uniform gap in the ground state can appear when the time-reversal (TR) symmetry is spontaneously broken by interactions. On the other hand, a correlated two-particle backscattering term by an impurity can become relevant while keeping the TR invariance. The Kondo effect in such a liquid exhibits new features in the structure of the screening cloud.