Effect of Disorder on Magnetism and Electronic Structure in Kagome Alloy Fe₂MnSn

Iron-based magnets with the Kagome lattice are a rich set of materials due to their non-trivial topology combined with high magnetic ordering temperature (Tc). Previously, we identified and synthesized Fe₂MnSn as a promising material with high magnetic anisotropy characterized by a high Tc. The desirable magnetic properties of ternary alloys are controlled by atomic-level antisite disorder and are sensitive to stoichiometry as well. To illustrate the role of disorder in Fe₂MnSn, we performed DFT calculations using 64-atom supercells, which enabled us to probe changes in the density of states and magnetic moments by design. Our data show that substitution of Mn for Sn modifies the system and reduces the total magnetization, consistent with experiments. Specifically, substitution studies find the total magnetic moment decreases from 7.0 µB/f.u. for Fe₂MnSn to 6.14 µB/f.u. for Fe₂Mn_1.25Sn_0.75. Unlike Mn, which prefers only anti-parallel alignment at Sn sites with respect to the Kagome lattice, Fe stabilizes in both parallel and anti-parallel configurations. We present the effect of such disorder on the density of states and related physical properties, providing new insight into how Kagome alloys can be tuned for spintronic functionality.