Spin and stability of on-surface synthesized Ni-organic complexes on Au (111)

초록

Planar metal-organic complexes of transition metals and it-conjugated ligands are of broad interest due to their high electric conductivity and functional tunability. The electronic and spin states of the transition metals play a central role in defining their functional properties. While Ni is generally expected to exhibit no magnetic moment upon donating two electrons, new cases with magnetic moment induced by surface environments have been reported, calling for further experimental examples. Here, we investigated the electronic and spin states of on-surface synthesized metal-organic complexes composed of Ni atoms and deprotonated 2,3,6,7,10,11-hexahy-droxytriphenylene (HHTP) on Au(111) using scanning tunneling microscopy and spectroscopy. Several structures including one with a three-blade fan shape were observed with two distinct Ni sites-bridge and end positions. Density functional theory calculations reveal that the bridge-position Ni is non-magnetic, while the end-position Ni is magnetic, explaining the peaks observed in experiments. Our calculation results also showed that the Au(111) surface significantly stabilized the structures compared to vacuum conditions. This study highlights the crucial role of Au(111) surface in determining the spin and stability properties of on-surface synthesized metal-organic complexes.

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