Theoretical Study of Intrinsic Ferromagnetic to Antiferromagnetic Switching in Two-Dimensional Fe/Cocl2 Monolayers Encapsulated in Uio–67 Mof Via Edge Termination

Abstract

Density Functional Theory (DFT) calculations are used to study the magnetic properties of two dimensional (2D) Fe/CoCl2 structures recently synthesized inside a derivative of UiO–67 Metal–Organic Framework (MOF). Both structures found stable in their high spin ground state with large intrinsic magnetic moments at each metal site. The calculated magnetic moments of Fe/CoCl2 structures are on average 3.75 𝜇𝛽/Fe and 2.30 𝜇𝛽/Co. These values are close to what is expected for Fe+2/Co+2 cations in a d6 and d7 electronic configurations with four and three unpaired electrons in their high spin states respectively. According to the calculated nearest neighbor (NN) magnetic exchange coupling constants (J's), superexchange interactions among metal cations are FerroMagnetic (FM) in FeCl2 and AntiFerroMagnetic (AFM) in CoCl2. All interactions become AFM in the presence of [Fe/CoCl4]−2 groups at the outer edge of both structures within the MOF's pore environment.

Keywords: Ab initioMagnetic PropertiesMonte CarloTransition Metal HalideMagnetic Exchange Coupling Constant