Electronic structure of above-room-temperature van der Waals ferromagnet Fe₃GaTe₂

A van der Waals (vdW) ferromagnet with high Curie temperature (T_C) has been highly pursued for better understanding robust long-range spin order in two-dimension (2D) and for developing its potential applications in spintronic devices. Fe₃GaTe₂, a newly discovered vdW ferromagnet with intrinsic ferromagnetism above room temperature, makes it necessary to have a comprehensive understanding of the microscopic origins of its higher T­_C. In this talk, we present the electronic structure of Fe₃GaTe₂ in its ferromagnetic ground state using angle-resolved photoemission spectroscopy (ARPES) and density-functional theory (DFT) calculations. Our results reveal a notable shift in chemical potential of Fe₃GaTe₂, compared to its sister material, Fe₃GeTe₂, while retaining similarities in overall electronic band structure. Based on DFT calculation, we elucidate the critical contribution of the Heisenberg exchange interaction (J_ex) and magnetic anisotropy energy (MAE) to the development of the high T­_C ferromagnetic ordering in Fe₃GaTe₂. Specifically, the J_ex parameter related to the out-of-plane interactions is significantly enhanced due to the decreased c-lattice constant in Fe₃GaTe₂. These findings provide valuable insights into the underlying electronic structure and its correlation with the emergence of high T­_C ferromagnetic ordering in Fe₃GaTe₂.