  Thin epitaxial films of Tb metal were grown on a clean W(110) substrate in
ultra-high vacuum and studied in-situ by low-energy electron microscopy.
Annealed films present magnetic contrast in spin-polarized low-energy electron
microscopy. The energy dependence of the electron reflectivity was determined
and a maximum value of its spin asymmetry of about 1\% was measured. The
magnetization direction of the Tb films is in-plane. Upon raising the
temperature, no change in the domain distribution is observed, while the
asymmetry in the electron reflectivity decreases when approaching the critical
temperature, following a power law $ \sim (1 - T/T_C)^\beta$ with a critical
exponent $\beta$ of 0.39.
