Akademik Veri Yönetim Sistemi
Computational Materials Science, cilt.271, 2026 (SCI-Expanded, Scopus)
The magnetic ground states of RI2 (R = La, Tb, and Y) monolayers are commonly investigated using relatively small computational supercells, which may limit the description of extended magnetic interactions. In this work, we examine the influence of supercell size on the magnetic properties of RI2 monolayers using first-principles density functional theory calculations. While calculations performed within a 2 × 2 supercell suggest a ferromagnetic ground state, our results show that larger 4 × 4 supercells allow additional magnetic configurations to become accessible. In particular, the RI2 (R = Tb, Y) monolayers are found to stabilize a columnar antiferromagnetic (CAFM) ground state when long-range interactions are included. To further investigate the magnetic behavior of the YI2 monolayer, the exchange interaction parameters (J1, J2, and J3) were extracted from DFT calculations and incorporated into an Ising model framework. Using the Creutz cellular automaton method, we analyze the finite-temperature magnetic properties and identify a first-order transition from the CAFM phase to the paramagnetic state at approximately 160 K. Our results demonstrate that the predicted magnetic ordering in two-dimensional rare-earth iodide monolayers strongly depends on the size of the computational supercell, providing a more reliable computational framework for future studies of magnetic two-dimensional materials.