Anomalous behavior of localized magnetic moments in itinerant ferromagnets Ln2Co12P7 (Ln = Y, Pr, Nd, Sm, Gd and Dy)

Abstract

We synthesized polycrystalline samples of ternary compounds Ln2Co12P7 (Ln = Y, Pr, Nd, Sm, Gd and Dy) with the Curie temperature being about 150 K and measured magnetization to clarify magnetism of Co sublattice and also to clarify behavior of magnetic moments of Ln3+ in ferromagnetic phase. As a result, magnetism of Y2Co12P7 was found to be a possible weakly itinerant electronic ferromagnetism and found to be similar to that of Lu2Co12P7, indicating that magnetism of Co sublattice does not change with Ln. From results for Ln2Co12P7, we found that spin components of magnetic moments of Ln3+ ferromagnetically couple with exchange field of ferromagnetic moments of Co sublattice. This result means that behavior of magnetic moments of Ln3+ can be described as the single ion model applied to the permanent magnets (LnCo5, Ln2Fe14B etc.) though the sign of coupling constant is opposite of the cases of permanent magnets. This is because magnetic moments of Co and Ln couple through P, not a direct coupling in cases of permanent magnets.