Magnetic ground state of monolayer CeI$_{2}$: occupation matrix control and DFT+U calculations

TL;DR

This study uses advanced DFT+U calculations with occupation matrix control to determine the magnetic ground state of monolayer CeI$_{2}$, revealing its ferromagnetic nature, magnetic anisotropy, and a Curie temperature of 128 K.

Contribution

It introduces occupation matrix control in DFT+U calculations to accurately identify the magnetic ground state of monolayer CeI$_{2}$, addressing metastable state challenges.

Findings

Ferromagnetic ground state confirmed with different magnetic parameters.

Estimated Curie temperature of 128 K for monolayer CeI$_{2}$.

Spin-orbit coupling is essential for magnetic anisotropy and electronic state description.

Abstract

The magnetic ground state is crucial for the applications of the two-dimension magnets as it decides fundamental magnetic properties of the material, such as magnetic order, magnetic transition temperature, and low-energy excitation of the spin waves. However, the simulations for magnetism of local-electron systems are challenging due to the existence of metastable states. In this study, occupation matrix control (OMC) and density functional theory plus Hubbard $U$ calculations are applied to investigate the magnetic ground state of monolayer CeI$_{2}$. Following the predicted ferromagnetic (FM) order, the FM ground state and the FM metastable states are identified and found to have different values of the magnetic parameters. Based on the calculated magnetic parameters of the FM ground state, the Curie temperature is estimated to be $128$ K for monolayer CeI$_{2}$. When spin-orbit coupling (SOC) is considered, the FM ground state is further confirmed to contain both off-plane and in-plane components of magnetization. SOC is shown to be essential for reasonably describing not only magnetic anisotropy but also local electronic orbital state of monolayer CeI$_{2}$.