Quantum Phase Transition and Protected Ideal Transport in a Kondo Chain

A. M. Tsvelik, O. M. Yevtushenko

Published 2015-06-21Version 1

We study the low energy physics of a Kondo chain where electrons from a one-dimensional band interact with magnetic moments via an anisotropic exchange interaction. It is demonstrated that the anisotropy gives rise to two different phases which are separated by a quantum phase transition. In the phase with easy plane anisotropy, Z$_2$ symmetry between sectors with different helicity of the electrons is broken. As a result, gapless excitations are insensitive to the potential disorder and the dc transport becomes symmetry protected. This effect is similar to the protection of the edge transport in time-reversal invariant topological insulators. The phase with easy axis anisotropy corresponds to the Tomonaga-Luttinger liquid with a pronounced spin-charge separation. The slow charge density wave modes can be pinned by the potential disorder.