The Helical Liquid and the Edge of Quantum Spin Hall Systems
Abstract
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.
Cite
@article{arxiv.cond-mat/0508273,
title = {The Helical Liquid and the Edge of Quantum Spin Hall Systems},
author = {Congjun Wu and B. Andrei Bernevig and Shou-Cheng Zhang},
journal= {arXiv preprint arXiv:cond-mat/0508273},
year = {2007}
}
Comments
4 pages, accepted by Phys. Rev. Lett