Electronic structure of thin film iron-tetracyanoethylene: Fe(TCNE)x

Pramod Bhatt, E. Carlegrim, A. Kanciurzewska, Machiel Pieter de Jong, M. Fahlman

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    Thin film iron-tetracyanoethylene Fe(TCNE)x, x ~ 2, as determined by photoelectron spectroscopy, was grown in situ under ultra-high vacuum conditions using a recently developed physical vapor deposition-based technique for fabrication of oxygen- and precursor-free organicbased molecular magnets. Photoelectron spectroscopy results show no spurious trace elements in the films, and the iron is of Fe²+ valency. The highest occupied molecular orbital of Fe(TCNE)x is located at ~1.7 eV vs. Fermi level and is derived mainly from the TCNE− singly occupied molecular orbital according to photoelectron spectroscopy and resonant photoelectron spectroscopy results. The Fe(3d)- derived states appear at higher binding energy, ~4.5 eV, which is in contrast to V(TCNE)2 where the highest occupied molecular orbital is mainly derived from V(3d) states. Fitting ligand field multiplet and charge transfer multiplet calculations to the Fe L-edge near edge X-ray absorption fine structure spectrum yields a high-spin Fe²+ (3d6) configuration with a crystal field parameter 10Dq ~ 0.6 eV for the Fe(TCNE)x system. We propose that the significantly weaker Fe-TCNE ligand interaction as compared to the room temperature magnet V(TCNE)2 (10Dq ~ 2.3 eV) is a strongly contributing factor to the substantially lower magnetic ordering temperature (TC) seen for Fe(TCNE)x - type magnets.
    Original languageUndefined
    Article number10.1007/s00339-008-5032-y
    Pages (from-to)131-138
    Number of pages8
    JournalApplied physics A: Materials science and processing
    Issue number131
    Publication statusPublished - 19 Dec 2008


    • METIS-264141
    • IR-69010
    • EWI-16488
    • SMI-NE: From 2006 in EWI-NE

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