OsPd bimetallic dimer pushes the limit of magnetic anisotropy in atom-sized magnets for data storage

The growing gap between the volume of digital data being created and the extent of available storage capacities stimulates intensive research into surface-supported, well-ordered array of atom-sized magnets that represents the ultimate limit of magnetic data storage. Anchoring transition metal heterodimers in vacancy defects in the graphene lattice has been identified as a vivid strategy to achieve large magnetic anisotropy energy (MAE) up to 80 meV with an easy axis aligned along the dimer bond. In this paper we have made a significant leap forward finding out MAE of 119 meV for an OsPt dimer and 170 meV for an OsPd dimer bound to a single nitrogen-decorated vacancy defect. The system with the highest MAE and with the theoretical storage density of  490 Tb inch^-2pushes the current limit of theoretical blocking temperature in graphene-supported transition-metal dimers from ~20 K to ~44 K assuming the relaxation time of 10 years. The mechanism of the enhanced MAE is discussed.