Large Magnetic\nAnisotropy in van der Waals Ferromagnet\nFe<sub>3</sub>GaTe<sub>2</sub> above Room Temperature

Discoveries of above-room-temperature intrinsic ferromagnetism\nin two-dimensional (2D) van der Waals (vdW) materials offer a platform\nfor studying fundamental 2D magnetism and spintronic devices, especially\nthe recently discovered above-room-temperature 2D vdW Fe<sub>3</sub>GaTe<sub>2</sub> (FGaT). However, the magnetic mechanism in FGaT\nremains elusive. Here, a detailed investigation using magnetic force\nmicroscopy on the thickness-dependent magnetic behavior of FGaT single\ncrystals is reported. The Heisenberg exchange interaction constant\n(<i>J</i>) at room temperature is determined to be 1.32836\n× 10<sup>–12</sup> J/m. Our study combining angle-resolved\nphotoemission spectroscopy and density functional theory suggests\nthat the high Curie temperature in FGaT is attributed to the shift\nof the localized Fe <i>d</i> band toward the Fermi level\nas well as the enhanced magnetic exchange effect due to the strong\nitinerant ability of Fe. This work sheds light on the understanding\nof magnetism in FGaT and provides a promising platform to investigate\nthe mechanisms of 2D magnetic materials.