Determining the structural stability of monolayer CeSiI via first principles

Recently, two-dimensional (2D) van der Waals materials have attracted significant interest due to their exotic electronic, optical and magnetic properties. The f-electron van der Waals materials provide an opportunity to merge the intrinsic flat band character into the low dimension, enabling a vast tunability for emergent phenomena like exotic magnetism, unconventional superconductivity, and the heavy fermion behavior. CeSiI was predicted via machine mining [1] , and experimentally confirmed [2], to be a 2D van der Waals heavy fermion flat band system. We use first-principles density functional theory (DFT) to perform phonon calculations to determine if the material is dynamically stable, and electronic calculations to better understand bonding. Our preliminary results are the first steps in understanding lattice-spin coupling in f-electron 2D materials.

[1] Jang, B.G., Lee, C., Zhu, JX. et al. Exploring two-dimensional van der Waals heavy-fermion material: Data mining theoretical approach. npj 2D Mater Appl 6, 80 (2022). https://doi.org/10.1038/s41699-022-00357-x

[2] Posey, V.A., Turkel, S., Rezaee, M. et al. Two-dimensional heavy fermions in the van der Waals metal CeSiI. Nature 625, 483–488 (2024). https://doi.org/10.1038/s41586-023-06868-x