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Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface

Abstract

Magnetic atoms at surfaces are a rich model system for solid-state magnetic bits exhibiting either classical1,2 or quantum3,4 behaviour. Individual atoms, however, are difficult to arrange in regular patterns1,2,3,4,5. Moreover, their magnetic properties are dominated by interaction with the substrate, which, as in the case of Kondo systems, often leads to a decrease or quench of their local magnetic moment6,7. Here, we show that the supramolecular assembly of Fe and 1,4-benzenedicarboxylic acid molecules on a Cu surface results in ordered arrays of high-spin mononuclear Fe centres on a 1.5 nm square grid. Lateral coordination with the molecular ligands yields unsaturated yet stable coordination bonds, which enable chemical modification of the electronic and magnetic properties of the Fe atoms independently from the substrate. The easy magnetization direction of the Fe centres can be switched by oxygen adsorption, thus opening a way to control the magnetic anisotropy in supramolecular layers akin to that used in metallic thin films8,9,10,11.

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Figure 1: Planar supramolecular layers of Fe–TPA complexes self-assembled on Cu(100).
Figure 2: Circularly polarized X-ray absorption spectra of Fe(TPA)4, O2–Fe(TPA)4 and Fe/Cu(100) measured at the Fe L2,3-edge and calculated multiplet structure.
Figure 3: Element-selective magnetization curves of the Fe centres and crystal-field diagrams.

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Acknowledgements

We acknowledge the ESRF for provision of beam time. Partial financial support was received through the EUROCORES 05-SONS-FP-009 SANMAG project of the European Science Foundation. P.G. and S.S. acknowledge financial support from the Spanish Ministerio de Educación y Ciencia (SYNSPIN—MAT2007-62341).

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Correspondence to Pietro Gambardella.

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Gambardella, P., Stepanow, S., Dmitriev, A. et al. Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface. Nature Mater 8, 189–193 (2009). https://doi.org/10.1038/nmat2376

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