Enhanced Magnetic Interaction between Ga and Fe in Two-Dimensional van der Waals Ferromagnetic Crystal Fe3GaTe2

Fe3GaTe2, a recently discovered van der Waals ferromagnetic crystal with the highest Curie temperature and strong perpendicular magnetic anisotropy among two-dimensional (2D) magnetic materials, has attracted significant attention and makes it a promising candidate for next-generation spintronic applications. Compared with Fe3GeTe2, which has the similar crystal structure, the mechanism of the enhanced ferromagnetic properties in Fe3GaTe2 is still unclear and needs to be investigated. Here, by using x-ray magnetic circular dichroism measurements, we find that both Ga and Te atoms contribute to the total magnetic moment of the system with antiferromagnetic coupling to Fe atoms. Our first-principles calculations reveal that Fe3GaTe2 has van Hove singularities at the Fermi level in nonmagnetic state, resulting in the magnetic instability of the system and susceptibility to magnetic phase transitions. In addition, the calculation results about the density of states in ferromagnetic states of two materials suggest that the exchange interaction between Fe atoms is strengthened by replacing Ge atoms with Ga atoms. These findings indicate the increase of both the itinerate and local moments in Fe3GaTe2 in view of Stoner and exchange interaction models, which results in the enhancement of the overall magnetism and a higher Curie temperature. Our work provides insight into the underlying mechanism of Fe3GaTe2's remarkable magnetic properties and has important implications for searching 2D materials with expected magnetic properties in the future.