Crystal structures and ferromagnetism of FexWN2 (x ∼ 0.74, 0.90) with defective iron triangular lattice

Graphical abstract: - Highlights: • Crystal structures of FexWN2 with defective iron triangle lattice were determined. • Fe0.74WN2 phase showed weak ferromagnetism at 300 K. • Decrease in temperature to 5 K suppressed ferromagnetism. • Approximately quarter defect is likely attributed to ferromagnetism. - Abstract: The crystal structures of FexWN2 (x ∼ 0.74, 0.90) and their magnetic properties were investigated. The structural studies reveal the formation of ion defects with different concentrations in the two-dimensional iron triangular lattice by analyzing the synchrotron radiation X-ray diffraction data. The magnetic measurements demonstrate that the Fe0.74WN2 phase shows ferromagnetism at 300 K, while the less defective Fe0.90WN2 phase exhibits no ferromagnetism. A decrease of temperature to 5 K significantly suppresses the room-temperature ferromagnetism of the Fe0.74WN2 phase. We attribute the emergence of ferromagnetism in FexWN2 to the increases of defect concentration and thermal displacement in the iron triangular lattice