Magnetic structure in the two-dimensional van der Waals ferromagnet Fe3GaTe2.

High-quality single crystals of the two-dimensional van der Waals ferromagnet Fe3GaTe2 (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 per-formed using single-crystal X-ray and neutron diffraction. The results confirm that FGaT crystallizes in the hexagonal P63/mmc structure, with Fe occupying two inequivalent sites (Fei and Feii), where the magnetic moment of Fei [1.9 (2) μB] is larger than that of Feii [1.4 (6) μB]. The magnetic easy axis is oriented along the c axis and the Curie temperature (T C) is approximately 355-360 K. Compared with Fe3GeTe2 (FGT), FGaT exhibits a slightly expanded a axis and a contracted c axis, resulting in a reduction in the Fei-Fei 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.