Easy axis of magnetization of Fe3C prepared by an electrolytic extraction method

•It is proved that the easy axis of cementite is c-axis of orthorhombic structure.•The precise magnetic anisotropy energy of cementite has been evaluated.•The method used in this article can be widely applicable for other materials.

We have determined the easy axis of magnetization of Fe3C (cementite) using a powder specimen prepared by an electrolytic extraction method. The easy axis is determined to be the c-axis (the shortest axis) of the orthorhombic structure with the space group Pnma. The result is different from the one previously reported by neutron diffraction (b-axis). The magnetic energy difference between the easy axis and the average of other two axes is approximately 400 kJ/m3 at 5 K.