Europium Cyclooctatetraene Nanowire Carpets: a Low-Dimensional, Organometallic, and Ferromagnetic Insulator.

Author(s) Huttmann, F.; Rothenbach, N.; Kraus, S.; Ollefs, K.; Arruda, L.M.; Bernien, M.; Thonig, D.; Delin, A.; Fransson, J.; Kummer, K.; Brookes, N.B.; Eriksson, O.; Kuch, W.; Michely, T.; Wende, H.
Journal J Phys Chem Lett
Date Published 2019 Feb 04

We investigate the magnetic and electronic properties of europium cyclooctatetraene nanowires (EuCot) by means of low-temperature x-ray magnetic circular dichroism (XMCD) and scanning tunneling microscopy (STM) and spectroscopy (STS). The EuCot nanowires are prepared in situ on a graphene surface. STS measurements identify EuCot as a wide-band-gap semiconductor with a band gap of 2.3 eV. By means of Eu M edge XMCD, orbital and spin magnetic moments of (-0.1 ±0.3) μ and (+7.0 ±0.6) μ, respectively, were determined. Field-dependent measurements of the XMCD signal at the Eu M edge show hysteresis for grazing x-ray incidence at 5 K, thus confirming EuCot as a ferromagnetic material. Our density functional theory calculations reproduce the experimentally observed bandgap. Modelling the experimental results theoretically, we find that the effective interatomic exchange interaction between Eu atoms is of the order of meV, that magnetocrystalline anisotropy energy is roughly half as big and that dipolar energy is approximately ten times lower.

DOI 10.1021/acs.jpclett.8b03711
ISSN 1948-7185
Citation J Phys Chem Lett. 2019.

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