  Two-dimensional (2D) surface of the topological materials is an attractive
channel for the electrical conduction reflecting the linearly-dispersive
electronic bands. By applying a reliable systematic thickness t dependent
measurement of sheet conductance, here we elucidate the dimensionality of the
electrical conduction paths of a Weyl semimetal Co3Sn2S2. Under the
ferromagnetic phase, the 2D conduction path clearly emerges in Co3Sn2S2 thin
films, indicating a formation of the Fermi arcs projected from Weyl nodes.
Comparison between 3D conductivity and 2D conductance provides the effective
thickness of the surface conducting region being estimated to be approximately
20 nm, which is rather thicker than 5 nm in topological insulator Bi2Se3. This
large value may come from the narrow gap at Weyl point and relatively weak
spin-orbit interaction of the Co3Sn2S2. The emergent surface conduction will
provide a pathway to activate quantum and spintronic transport features
stemming from a Weyl node in thin-film-based devices.
