  We report a longitudinal spin Seebeck effect (SSE) study in epitaxially grown
FeF2(110) antiferromagnetic (AFM) thin films with strong uniaxial anisotropy
over the temperature range of 3.8 - 250 K. Both the magnetic field- and
temperature-dependent SSE signals below the N\'eel temperature (TN=70 K) of the
FeF2 films are consistent with a theoretical model based on the excitations of
AFM magnons without any net induced static magnetic moment. In addition to the
characteristic low-temperature SSE peak associated with the AFM magnons, there
is another SSE peak at TN which extends well into the paramagnetic phase. All
the SSE data taken at different magnetic fields up to 12 T near and above the
critical point TN follow the critical scaling law very well with the critical
exponents for magnetic susceptibility of 3D Ising systems, which suggests that
the AFM spin correlation is responsible for the observed SSE near TN.
