Magnetic anisotropy and phononic properties of two-dimensional ferromagnetic FeGeS monolayer.

In 2023, FeGeS monolayer with Curie temperature of 630 K is predicted, which is promising to be used in next-generation spintronic devices. However, its magnetic anisotropy and phononic properties are still unclear. In this paper, we implemented the first-principles calculations on FeGeS monolayer, and found its ferromagnetic ground state with robustness to the -1.5%-1.3% biaxial strain. Meanwhile, the out-of-plane magnetic anisotropy dominated by dipolar interaction is found in FeGeS monolayer. Finally, we studied the phononic properties to identify the dynamical stability of FeGeS monolayer and highlight the contribution from the anharmonic interaction of optical phonons to the thermal expansion coefficient. We also find two single-phonon modes can be used to design quantum mechanical resonators with a wide cool-temperature range. These results can provide a comprehensive understanding of the magnetism and phonon properties of two-dimensional (2D) FeGeS, beneficial for the application of 2D FeGeS in spintronics.