Enhancing Intrinsic Magnetic Hardness by Modulating Antagonistic Interactions in the Rare‐Earth‐Free Magnetic Solid Solution Hf2Fe1−δRu5−xIrx+δB2.

The quinary members in the solid solution Hf2Fe1−δRu5−xIrx+δB2 (x=1–4, VE=63–66) have been investigated experimentally and computationally. They were synthesized via arc‐melting and analyzed by EDX and X‐ray diffraction. Density functional theory (DFT) calculations predicted a preference for magnetic ordering in all members, but with a strong competition between ferro‐ and antiferromagnetism arising from interchain Fe−Fe interactions. The spin exchange and magnetic anisotropy energies predicted the lowest magnetic hardness for x=1 and 3 and the highest for x=2. Magnetization measurements confirm the DFT predictions and demonstrate that the antiferromagnetic ordering (TN=55–70 K) found at low magnetic fields changed to ferromagnetic (TC=150–750 K) at higher fields, suggesting metamagnetic behavior for all samples. As predicted, Hf2FeRu3Ir2B2 has the highest intrinsic coercivity (Hc=74 kA/m) reported to date for Ti3Co5B2‐type phases. Furthermore, all coercivities outperform that of ferromagnetic Hf2FeIr5B2, indicating the importance of AFM interactions in enhancing magnetic anisotropy in these materials. Importantly, two members (x=1 and 4) maintain intrinsic coercivities in the semi‐hard range at room temperature. This study opens an avenue for controlling magnetic hardness by modulating antagonistic AFM and FM interactions in low‐dimensional rare‐earth‐free magnetic materials. [ABSTRACT FROM AUTHOR]