Growth and structure of Ag on bilayer Co nanoislands on Cu(111)

Abstract

We have studied the growth of Ag on bilayer high Co nanoislands on Cu(111) using scanning tunneling microscopy. Noble metal capping of magnetic nanostructures is known to influence the magnetism and knowledge of the growth is therefore important. We find that Ag preferentially nucleates on the Co nanoislands, initially leaving the free Cu sites clean. Furthermore we observe that those Co islands which are capped with Ag are almost completely capped, thus making a perfect multilayered system of Ag/Co/Cu(111). We observe a (9 × 9) reconstruction of the Ag overlayer on Co/Cu(111).

Molecular self-assembly at nanometer scale modulated surfaces: trimesic acid on Ag(111), Cu(111) and Ag/Cu(111)

“…[21][22][23][24] These kind of weak reconstructions and Moire ´patterned surface systems have been seen for many materials. [25][26][27][28][29][30] We will compare the self-assembly of TMA on this modulated surface with the flat surfaces of Ag(111) and Cu (111). Changing the balance between molecule-molecule and molecule-surface interaction is shown to have a drastic effect on the self-assembly: we will demonstrate that the molecular self-assembly of TMA at room temperature is strongly disturbed due to the modulated substrate as long as TMA is interacting via fairly weak hydrogen bonding, whereas annealing allows a stronger intermolecular interaction via ionic hydrogen bonds that leads to a new well-ordered phase with shape and symmetry steered by the substrate.…”

An approach for patterned molecular adsorption on ferromagnets, achieved via Moiré superstructures

“…Pure Co islands on Cu(111) grow pseudomorphically and to design an ordered adsorption template for V(O)salen on Co islands on Cu(111), Ag is added as an additional component, forming bi-metallic layered Ag-Co island heterostructures on the Cu(111) substrate. 23 This is performed by first depositing Co and then Ag to the Cu(111) substrate at RT, followed by a sample transfer to the STM operated at 77 K. Both directly on Cu(111) 42 and on the Co-islands on Cu(111), [22][23][24] Ag forms hexagonal Moire ´superstructures. This imposes a periodic structured surface as seen in the inset of Fig.…”

“…Such an adsorption template can be obtained by introducing metallic adlayers with a lattice mismatch to the underlying crystal. Typically, this leads to Moire ´patterns or reconstructions in the top surface layer that are accompanied by a modulated electronic structure with a periodicity of a few nanometers across the surface that can serve as a template for adsorption [20][21][22][23][24] By introducing ferromagnetic layers to the substrate, it is in addition to the lateral steering due to the modulation, also possible to use the exchange coupling in the vertical direction between the magnetic layer of the substrate and the magnetic moment of relevant metal-organic molecules. This can stabilize their magnetic properties against thermal fluctuations.…”

“…Namely the Co/Ag(111) and the Ag/Co/Cu(111) systems as the top surface layer of both surfaces reconstruct in a hexagonal Moire ´superstructure, with the potential to steer the adsorption of molecules. [21][22][23] The ability to steer the molecular adsorption for the two kind of cobalt island substrates is here examined by introducing a paramagnetic metal-organic molecule from the salen-family, seen in Fig. 1.…”

Potential energy landscape of metallic Moiré patterns

“…The growth of silver on bilayer cobalt nanoislands on Cu(111) has recently been investigated [16]. It was found that at room temperature silver preferentially nucleates on top of cobalt islands and that these are either completely capped with 1 ML Ag or remain uncovered.…”