Effect of annealing temperature on competing structural phases of co-sputtered Fe-Mn-Sn films near an atomic ratio of 2:1:1

Research in recent years has focused on the thin-film synthesis of high-quality ternary alloys, identified for their tunable properties and potential in spintronics (e.g., Heusler alloys, Kagome magnets). In a previous study, we identified the conditions to stabilize Fe2MnSn, a Kagome magnet with a high Curie temperature and magnetic anisotropy. However, ternary phases such as Fe2MnSn are challenging to synthesize and stabilize within a narrow temperature window, as binary and elemental phases can also form during the growth process. To highlight these observations, we investigated the thin film phases in the Fe-Mn-Sn system near the 2:1:1 ratio as a function of annealing temperature, ranging from 400 to 700 °C. The elemental Fe, Mn, and Sn targets were pre-calibrated to a close to 2:1:1 ratio and co-sputtered at room temperature, followed by annealing. One binary Kagome magnet, Fe3Sn2, the hexagonal ferromagnet Fe5Sn3, along with the elemental Fe phase, are stabilized between 400-500 °C, but disappear above 550 °C, where Fe2MnSn is the only stable phase to about 700 °C, beyond which the elemental Mn phase also appears strongly. We will present several structure-property relationships to highlight such findings, utilizing apparatus for magnetotransport and the Magneto-Optic Kerr Effect.