Characteristics of Single-Molecule Magnet Dimers ([Mn3]2) on Graphene and h‑BN

With appropriate choice of ligands, Mn3-based single-molecule magnets (SMMs) can be covalently linked to form SMM dimers that exhibit either ferromagnetic (FM) or antiferromagnetic (AFM) ground state. We present here results of density functional theory (DFT)-based calculations that elucidate the effect of two different types of support, graphene and two-dimensional hexagonal boron nitride (h-BN), on the electronic structure and magnetic properties of the ligated Mn3 dimers. Our calculations for the spin per Mn3 monomer of both the FM and AFM configurations of the isolated Mn3 dimers in the gas phase agree with experimental results (S = 6) when the dimers are explicitly charged to a +2 state, the charged state found in experimental observations. Following the determination of the most stable configuration of each dimer on graphene and h-BN, the analysis of their spin reveals that their magnetic properties are not noticeably affected when adsorbed on these two-dimensional materials. The charge density, charge transfer, and binding analysis reveals that the dimers are physisorbed on both graphene and h-BN through van der Waals interactions, with charge transfer taking place in the case of graphene only. Our results provide insights into the design of proposed experiments for measuring transport properties of these AFM and FM dimers and the critical role played by graphene and h-BN as supports.