Abstract
In this paper we focus on the structural, electronic, and magnetic properties of Ni tetra-phenyl-porphyrins (NiTPP) grown on top of Fe(001)–p(1 × 1)O. Ordered thin films of metal TPP molecules are potentially interesting for organic electronic and spintronic applications, especially when they are coupled to a ferromagnetic substrate. Unfortunately, porphyrin layers deposited on top of ferromagnetic substrates do not generally show long-range order. In this work, we provide evidence of an ordered disposition of the organic film above the iron surface and we prove that the thin layer of iron oxide decouples the molecules from the substrate, thus preserving the molecular electronic features, especially the HOMO-LUMO gap, even when just a few organic layers are deposited. The effect of the exposure to molecular oxygen is also investigated and an increased robustness against oxidation with respect to the bare substrate is detected. Finally, we present our results for the magnetic analysis performed by spin resolved spectroscopy, finding a null magnetic coupling between the molecules and the substrate.
Highlights
The results acquired by Low Energy Electron Diffraction (LEED) and STM are shown
We showed that a single layer of Ni tetraphenyl-porphyrins (NiTPP) is arranged in an ordered commensurate (5 × 5) superpattern above the substrate
The thin oxide layer is responsible for the preservation of the electronic structure of the NiTPP system
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Micromachines 2021, 12, 191 have been studied by depositing them on top of insulating [20], semiconductive [21] and conductive substrates [22] Their open structure, with the phenyls not folded up on the macroring, allows to directly address the inner TM ion [23]. NiTPP/Fe–p(1 × 1)O, in order to understand whether (i) the ordering of the molecular layer is still preserved, (ii) the electronic features are maintained, (iii) the system is robust against gaseous contaminants, and (iv) the choice of Ni as the inner ion is effective to introduce a magnetic response of the system introducing an orientation of the magnetic moments carried by the molecules, with a detailed analysis expanding our preliminary results [33]
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