We present a theoretical study of relative stability, as well as of the magnetic and electronic properties, of ${\mathrm{AgF}}_2$ and ${\mathrm{CuF}}_2$, in two related structural forms: orthorhombic (ambient pressure form of ${\mathrm{AgF}}_2$) and monoclinic (ambient pressure form of ${\mathrm{CuF}}_2$), using density functional theory. We demonstrate that the $P{2}_1/c\to Pbca$ structural transition is associated with a weakening of the intrasheet magnetic superexchange ($|{\mathrm{J}}_{2\mathrm{D}}|$). This finding aligns with the flattening of two-dimensional (2D) layers, a smaller charge-transfer energy, and a stronger admixing of ${\mathrm{Ag}}_{\mathrm{d}}/{\mathrm{Cu}}_{\mathrm{d}}\text{−}{\mathrm{F}}_{\mathrm{p}}$ states in the monoclinic structure, compared to the orthorhombic form. Consequently, monoclinic ${\mathrm{AgF}}_2$ should be targeted in experiments as it is likely to exhibit stronger magnetic coupling than its orthorhombic counterpart. The dynamically stable $P{2}_1/c$ form of ${\mathrm{AgF}}_2$ could be achieved through two alternative paths: by applying negative strain or by rapidly quenching silver(II) difluoride from temperatures above 480 K to low temperatures.

• Received 9 November 2023
• Accepted 27 February 2024

DOI:https://doi.org/10.1103/PhysRevMaterials.8.034407