Ballistic transport of helical edge modes in two-dimensional topological insulators is protected by time-reversal symmetry. Recently it was pointed out [1] that coupling of non-interacting helical electrons to an array of randomly anisotropic Kondo i
mpurities can lead to a spontaneous breaking of the symmetry and, thus, can remove this protection. We have analyzed effects of the interaction between the electrons using a combination of the functional and the Abelian bosonization approaches. The suppression of the ballistic transport turns out to be robust in a broad range of the interaction strength. We have evaluated the renormalization of the localization length and have found that, for strong interaction, it is substantial. We have identified various regimes of the dc transport and discussed its temperature and sample size dependencies in each of the regimes.
We consider chiral electrons moving along the 1D helical edge of a 2D topological insulator and interacting with a disordered chain of Kondo impurities. Assuming the electron-spin couplings of random anisotropies, we map this system to the problem of
the pinning of the charge density wave by the disordered potential. This mapping proves that arbitrary weak anisotropic disorder in coupling of chiral electrons with spin impurities leads to the Anderson localization of the edge states.
