Electronic structure of thin film cobalt tetracyanoethylene, Co(TCNE)x
2010 (English)In: Synthetic metals, ISSN 0379-6779, Vol. 161, no 17-18, 1892-1897 p.Article in journal (Refereed) Published
V(TCNE)x, TCNE=tetracyanoethylene, x~2, is a semiconducting organicbased magnet and one of very few organic-based magnets with critical temperature above room temperature (RT). With the aim to understand the key design criteria for achieving RT organic-based magnets we have started to study the electronic and chemical structure of members of the M(TCNE)x family with significantly lower critical temperatures than V(TCNE)x. In this paper, Co(TCNE)x, x~2, (Tc~44 K, derived from its powder form) were prepared by a method based on physical vapor deposition, resulting in oxygen-free thin films. The results propose Co(TCNE)x to contain to local bonding disorder in contrast to V(TCNE)x thin films, which can be grown virtually defect free. In addition, the Co L-edge does not show any pronounced fine structure, suggesting the crystal field to be very weak. By using a variety of photoemission and X-ray absorption techniques the highest occupied molecular orbital (HOMO) of Co(TCNE)x was determined to mainly be TCNE-derived while the states originating from Co(3d) are localized at higher binding energies. This is in stark contrast to V(TCNE)x where V(3d) is mainly responsible for the HOMO. As the HOMO of Fe(TCNE)x (Tc~121 K, derived from its powder form) is TCNE-derived these results show that Co(TCNE)x is more similar to Fe(TCNE)x than to V(TCNE)x in terms of electronic structure.
Place, publisher, year, edition, pages
Elsevier , 2010. Vol. 161, no 17-18, 1892-1897 p.
IdentifiersURN: urn:nbn:se:liu:diva-56261DOI: 10.1016/j.synthmet.2011.06.031ISI: 000295564000016OAI: oai:DiVA.org:liu-56261DiVA: diva2:317831
Funding agencies|Swedish Research Council||Knut and Alice Wallenberg Foundation||2010-05-052010-05-052015-05-13