  We have investigated the critical behavior of a shandite-type half-metal
ferromagnet Co3Sn2S2. It exhibits a second-order paramagnetic-ferromagnetic
phase transition with TC = 174 K. To investigate the nature of the magnetic
phase transition, a detailed critical exponent study has been performed. The
critical components beta, gamma, and delta determined using the modified Arrott
plot, the Kouvel-Fisher method as well as the critical isotherm analysis are
match reasonably well and follow the scaling equation, confirming that the
exponents are unambiguous and intrinsic to the material. The determined
exponents of Co3Sn2S2 deviates from theoretical estimated short-range universal
models. Instead, Co3Sn2S2 exhibits long-range order in the nature of magnetic
interaction with the spin decay as J(r) ~ 1/r^[-(d + sigma)] with sigma = 1.28.
