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Title :A giant negative magnetoresistance effect in an iron tetrabenzoporphyrin complex
Authors :Nishi, Miki
Ikeda, Mitsuo
Kanda, Akinori
Hanasaki, Noriaki
Hoshino, Norihisa
Akutagawa, Tomoyuki
Matsuda, Masaki
Issue Date :14-Nov-2016
Citation jtitle :Dalton Transactions
vol. :45
start page :16604
end page :16609
Abstract :By measuring the electrical resistivity in TPP[FeIII(tbp)(CN)2]2 (TPP = tetraphenylphosphonium and tbp = tetrabenzoporphyrin) under the application of a static magnetic field, a giant negative magnetoresistance (MR) effect with high anisotropy is observed. More specifically, the MR ratio at 13 K under a field of 9 T perpendicular to the c axis is −70%, whereas the MR ratio under a field parallel to the c axis is −40%. Furthermore, electron spin resonance (ESR) measurements indicate large anisotropy in the principal g-values of d spin (S = 1/2) in the [FeIII(tbp)(CN)2] unit; the g1 value almost perpendicular to the tbp plane and the g2 and g3 values almost parallel to the tbp plane are 3.60, 1.24, and 0.39, respectively. It is revealed that the anisotropy in the MR effect arises from the anisotropy in the d spin, suggesting that the d spins in TPP[FeIII(tbp)(CN)2]2 affect the π-conduction electron via the intramolecular π–d interaction. The anisotropy and magnitude in the giant negative MR effect for TPP[FeIII(tbp)(CN)2]2 are smaller than the corresponding values for the isostructural phthalocyanine (Pc) analogue TPP[FeIII(Pc)(CN)2]2. This is consistent with the fact that the intermolecular antiferromagnetic d–d interaction in TPP[FeIII(tbp)(CN)2]2 (suggested by the Weiss temperature: Θ = −8.0 K) is weaker than that in TPP[FeIII(Pc)(CN)2]2 (Θ = −12.3 K). This indicates that the minor modification in coordination complexes can significantly affect the MR effect via tuning the intermolecular d–d interaction as well as the intermolecular π–π overlap.
URL :http://pubs.rsc.org/en/content/articlelanding/2016/dt/c6dt01911k#!divAbstract
Type Local :プレプリント
ISSN :14779226
Publisher :Royal Society of Chemistry
URI :http://hdl.handle.net/2298/38561
Appears in Collections:Journal Article (Sciende)
Please use this identifier to cite or link to this item: http://hdl.handle.net/2298/38561