Magnetic moments and exchange interaction in Sm(Co, Fe)5 from first-principles

The electronic structure, magnetization and exchange interaction in Sm(Co1−xFex)5 with x = 0–1 are studied from a first-principles density functional calculation. The dependence of the magnetization on Fe content shows a 3d-like Slater–Pauling relationship in these alloys. As the Fe content x increases from 0 to 1.0, the magnetization increases from 7.8 μB to 10.6 μB (x = 0.8) and then decreases to 10.0 μB (x = 1). The effective exchange interaction parameters show a peak value around x = 0.6, which is ascribed to the exchange parameters between Fe and Co being larger than those for Co–Co and Fe–Fe pairs. The estimated TC from the calculated exchange parameters range between 890 K and 1357 K in Sm(Co1−xFex)5 using a multi-sublattices mean field model.

Research highlights
► The calculated Sm 4f electronic configuration conforms to the Hund rules using GGA+U.
► The Fe content dependence of the magnetization show a 3d-like Slater–Pauling relationship in Sm(Co1−xFex)5 alloys.
► The exchange parameters between Fe and Co are larger than those for Co–Co and Fe–Fe pairs, and are responsible for the appearance of the peak in the value of Curie temperature in Sm(Co1−xFex)5.
► The estimated Curie temperature from the calculated exchange parameters varied from 890 K to 1357 K with x = 0–1.0 based on a multi-sublattice mean field model.