The ${\mathrm{Fe}}_3{\mathrm{GaTe}}_2$ compound was investigated using dynamic magnetic measurements, microscopic ${}^{57}\mathrm{Fe}$ Mössbauer spectroscopy, complemented by density functional theory (DFT) and Monte Carlo simulations. A reliable fitting scheme was developed for its Mössbauer spectra, yielding a complete set of hyperfine parameters from 5 K to above the Curie temperature. The opposite signs of the quadrupole splitting for the FeI and FeII sites indicate that the interactions at the FeI site are predominantly out-of-plane, in contrast to the primarily in-plane interactions at the FeII site. Furthermore, the temperature dependence of the hyperfine field shows that the magnetism of ${\mathrm{Fe}}_3{\mathrm{GaTe}}_2$ aligns more closely with the three-dimensional Heisenberg model. The Mössbauer spectra also reveal that intrinsic defects enhance spin fluctuations, as evidenced by the presence of a persistent paramagnetic component down to 5 K and significantly broadened linewidths. To understand the origin of these defects, we performed systematic DFT and Monte Carlo simulations. Our theoretical results demonstrate that such defects suppress the ferromagnetic transition temperature and suggest that the observed spin fluctuations are likely linked to FeII vacancies and/or FeII-Ga antisite defects.

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• Fine & hyperfine structure
• Ferromagnets
• Magnetic systems
• Mössbauer spectroscopy