Magnetic structure in the two-dimensional van der Waals ferromagnet Fe 3 GaTe 2

High-quality single crystals of the two-dimensional van der Waals ferromagnet Fe 3 GaTe 2 (FGaT) were successfully grown using the chemical vapour transport method, which effectively reduced surface impurities compared with conventional self-flux growth. Structural and magnetic characterizations were performed using single-crystal X-ray and neutron diffraction. The results confirm that FGaT crystallizes in the hexagonal P 6 3 / mmc structure, with Fe occupying two inequivalent sites (Fe i and Fe ii ), where the magnetic moment of Fe i [1.9 (2) μ B ] is larger than that of Fe ii [1.4 (6) μ B ]. The magnetic easy axis is oriented along the c axis and the Curie temperature ( T C ) is approximately 355–360 K. Compared with Fe 3 GeTe 2 (FGT), FGaT exhibits a slightly expanded a axis and a contracted c axis, resulting in a reduction in the Fe i –Fe i interatomic distance along the c axis. This pronounced contraction could strengthen the Fe–Fe exchange interaction, which is believed to be the key factor responsible for the significantly higher T C in FGaT relative to FGT.