Electronic structure and magnetic anisotropies of antiferromagnetic transition-metal difluorides

Abstract

We compare calculations based on density functional theory (DFT) with available experimental data and analyze the origin of magnetic anisotropies in ${\mathrm{MnF}}_{2}, {\mathrm{FeF}}_{2}, {\mathrm{CoF}}_{2}$, and ${\mathrm{NiF}}_{2}$. We confirm that the magnetic anisotropy of ${\mathrm{MnF}}_{2}$ stems almost completely from the dipolar interaction, while magnetocrystalline anisotropy energy (originating in spin-orbit interaction) plays a dominant role in the other three compounds, and discuss how it depends on the details of band structure. The latter is critically compared to available optical measurements. The case of ${\mathrm{CoF}}_{2}$, where magnetocrystalline anisotropy energy strongly depends on $U$ (the Hubbard parameter in $\mathrm{DFT}+\mathrm{U}$), is put into contrast with ${\mathrm{FeF}}_{2}$ where theoretical predictions of magnetic anisotropies are nearly quantitative.