The effect of Zr substitution on saturation magnetization in (Sm_1-xZr_x)(Fe_0.8Co_0.2)₁₂ compound with the ThMn₁₂ structure

Zr is one of the essential elements to stabilize the ThMn₁₂ structure in rare earth (R) transition metal (M) hard magnetic compounds, RM₁₂. In this work, the effects of Zr on the intrinsic hard magnetic properties of (Sm_1-x Zr_x)(Fe_0.8Co_0.2)₁₂ compounds are investigated using epitaxially grown thin films. The increase of Zr substitution for Sm from x = 0 to 0.26 for (Sm_1-x Zr_x)(Fe_0.8Co_0.2)₁₂ increases saturation magnetization (μ₀M_s) from 1.78 T to 1.90 T, the highest value reported for hard magnetic compounds. The largest μ₀H_a and T_c for Zr-doped samples were found to be 9.8 T and 671 K for x = 0.18 which is superior to those for Nd₂Fe₁₄B. Sm-rich Sm_1.30Zr_0.27(Fe_0.8Co_0.2)₁₂, obtained as sub-μm thick films, has remanence, μ₀M_r of 1 T, which appears to be useful for near-field applications such as micro-electro-machines and magnetic recording media if microstructure can be optimized to obtain a sufficient coercivity.