Two-Dimensional Ultrathin Fe₃Sn₂ Kagome Metal with Defect-Dependent Magnetic Property

Two-dimensional (2D) Fe₃Sn₂, which is a room-temperature ferromagnetic kagome metal, has potential applications in spintronic devices. However, the systematic synthesis and magnetic study of 2D Fe₃Sn₂ single crystals have rarely been reported. Here we have synthesized 2D hexagonal and triangular Fe₃Sn₂ nanosheets by controlling the amount of FeCl₂ precursors in the chemical vapor deposition (CVD) method. It is found that the hexagonal Fe₃Sn₂ nanosheets exist with Fe vacancy defects and show no obvious coercivity. While the triangular Fe₃Sn₂ nanosheet has obvious hysteresis loops at room temperature, its coercivity first increases and then remains stable with an increase in temperature, which should result from the competition of the thermal activation mechanism and spin direction rotation mechanism. A first-principles calculation study shows that the Fe vacancy defects in Fe₃Sn₂ can increase the distances between Fe atoms and weaken the ferromagnetism of Fe₃Sn₂. The resulting 2D Fe₃Sn₂ nanosheets provide a new choice for spintronic devices.