The capacity of investigate and tailor the materials properties down to nanoscale created new perspectives for the development of functional devices using single atoms or molecules. Concerning magnetism, the stabilization of magnetic remanence in single atoms represents the ultimate limit on the size reduction of storage devices. After recent advances in this field, lanthanides have emerged as promising candidates for atomic magnets. However, the high diffusion of single standing atoms hinder the development of real-world applications. The next step to further advance towards practical devices is the coordination of these atoms in networks preserving their outstanding magnetic properties.
The 4f-Mag project consisted in the preparation of metal-organic networks by on-surface synthesis and the investigation of their structural, electronic, and magnetic properties. The main goal was to coordinate lanthanides in regular molecular arrays preserving their functionality as single atom magnets, and also enhancing their intrinsic high magnetic anisotropy and large relaxation lifetime. This project ambitioned to explore the versatility of molecular linkers to further advance in the path to accomplish single atom magnets for functional devices. The specific objectives were:
(I) Coordinate the Ln atoms using molecules to design regular arrays of single atoms.
(II) Use the coordination networks to tailor the magnetic properties and thermal stability of lanthanides atoms.
Several systems were investigated, employing molecules with different functional linkers, as carboxylic acid, phenyl, cyanamide, thiol, and hydroxyl. These molecules were coordinated with Dy and Er atoms on metallic surfaces (Au(111), Cu(111) and Ag(111)) and also on graphene/Ir(111). For some of them it was possible to successfully prepare regular networks with long-range ordering, others did not coordinate or formed irregular structures. The properties of the systems that formed regular structures were investigated. The results demonstrated that it is possible to engineer the electronic and magnetic properties of lanthanides on surfaces by coordinative protocols.
