Magnetic Structure of SmCo₅ from 5 K to the Curie Temperature

The crystal and magnetic structure of SmCo₅ is determined by neutron powder diffraction between 5 K and the Curie temperature. In order to overcome the enormous neutron absorption of samarium, a ¹⁵⁴Sm isotopically enriched sample was used. The ordered magnetic moments of both crystallographically distinct cobalt atoms are not significantly different over the whole temperature range. They decrease from 2.2 μ_B at 5 K to about 0.6 μ_B at 1029 K. Samarium's ordered magnetic moment decreases from 1.0 μ_B at 5 K, runs through a minimum of 0.2 μ_B around 650 K, and becomes larger than cobalt's ordered magnetic moment above 950 K. No sign or orientation change of the samarium and cobalt ordered magnetic moments is found between the Curie temperature and 5 K. SmCo₅ is thus a ferromagnet and does not switch to a ferrimagnetic state as discussed in the literature.