  We present a first-principles study of the large magneto-crystalline
anisotropy in the intercalated di-chalcogenide material \ce{Fe_{0.25}TaS_2},
investigated with the DFT+U approach. We verify a uniaxial magnetocrystalline
anisotropy energy(MAE) of 15meV/Fe. in the material. We further analyze the
dependence of MAE on the constituent elements and the effect of spin-orbit
coupling. Contrary to conventional intuition, we find a small contribution to
MAE due to strong spin-orbit coupling in the heavier element, Ta. We show that
the electronic configuration, crystal field environment and correlational
effects of the magnetic ion are more important.
