  A two dimensional topological insulator exhibits helical edge states
topologically protected against single particle backscattering. Such protection
breaks down, however, when electron electron interactions are significant or
when edge reconstruction occurs, leading to suppressed density of states (DOS)
at Fermi level that follows universal scaling with temperature and energy,
characteristic of Tomonaga Luttinger liquid (TLL). Here, we grow multilayer
FeSe on SrTiO3 by molecular beam epitaxy, and observe robust edge states at
both {100}Se and {110}Se steps using scanning tunneling
microscopy/spectroscopy. We determine the DOS follows a power law, resulting in
Luttinger parameter K of 0.26 +/- 0.02 and 0.43 +/- 0.07 for {100}Se and
{110}Se edges, respectively. The smaller K for the {100}Se edge also indicates
strong correlations, attributed to ferromagnetic ordering likely present due to
checkerboard antiferromagnetic fluctuations in FeSe. These results demonstrate
TLL in FeSe helical edge channels, providing an exciting model system for novel
topological excitations arising from superconductivity and interacting helical
edge states.
