  Domain walls in fractional quantum Hall ferromagnets are gapless helical
one-dimensional channels formed at the boundaries of topologically distinct
quantum Hall (QH) liquids. Na\"{i}vely, these helical domain walls (hDWs)
constitute two counter-propagating chiral states with opposite spins. Coupled
to an s-wave superconductor, helical channels are expected to lead to
topological superconductivity with high order non-Abelian excitations. Here we
investigate transport properties of hDWs in the $\nu=2/3$ fractional QH regime.
Experimentally we found that current carried by hDWs is substantially smaller
than the prediction of the na\"{i}ve model. Luttinger liquid theory of the
system reveals redistribution of currents between quasiparticle charge, spin
and neutral modes, and predicts the reduction of the hDW current. Inclusion of
spin-non-conserving tunneling processes reconciles theory with experiment. The
theory confirms emergence of spin modes required for the formation of
fractional topological superconductivity.

Mesoscale and Nanoscale Physics;Quantum Gases;Strongly Correlated Electrons