Novel family of near-room-temperature compensated itinerant pyrochlore ferrimagnets, RInCo₄ ($R=$ Dy-Tm)

We successfully synthesized single crystals of a series of C15b Laves phase compounds, RInCo₄ ($R=$ Dy-Tm), with Co-pyrochlore and R-fcc sublattices, and systematically studied their magnetic properties via magnetometry measurements. These itinerant cubic compounds, with Curie temperatures above room temperature, show compensated ferrimagnetism featuring an antiferromagnetic coupling between the two sublattices. From this series, DyInCo₄ exhibits the highest TC (= 368 K) and a near-room-temperature compensation point Tcp (= 295 K). TC does not change drastically with the R atom, whereas Tcp depends on the de Gennes factor of R³⁺. Another magnetization anomaly is observed in all the compounds at low temperatures, which may be indicative of changes in the lattice or magnetic structure. The easy axis the ferrimagnetic moment of DyInCo₄, ErInCo₄, and TmInCo₄ is found at $T =$ 5 K to be along the [001], [111] and [110] directions, respectively. However, the simple easy-axis or easy-plane ferrimagnetic picture cannot be applied to HoInCo₄. These observations suggest that the R sublattice determines magnetic anisotropy and compensation, while the Co sublattice plays a role in strong magnetic ordering. The high Curie temperature, together with the magnetization compensation point near room temperature, renders these itinerant pyrochlore magnets interesting for spintronic applications.