π-d interaction in phthalocyanine conductors
Partially oxidized phthalocyanine conductors such as CoPc(AsF6)0.5 and NiPc(AsF6)0.5consist of one-dimensional double chain comprising a transition-metal and organic macrocycle chains. Each of these chains generates a narrow d-band and a wide π-band. The d-band is located near the Fermi level of the π-conduction-band. The interplay between these π- and d-bands will be introduced. The first examples of the interplay is the influence of the magnetic moments of unpaired d-electrons at the Co site to the itinerant π-holes on Pc chain. The exchange coupling with these magnetic moments suppresses the coherent motion of π-holes in CoPc(AsF6)0.5. This conclusion was derived from the comparative study of the isostructural conductors, non-magnetic NiPc(AsF6)0.5 and magnetic CoPc(AsF6)0.5. Another example is the transfer of holes from π-to d-band which is induced by high pressure. This charge transfer occurs at 0.5 GPa and continues up to 6 GPa in NiPc(AsF6)0.5.. The same phenomenon was observed in CoPc(AsF6)0.5 as well. A metal-nonmetal transition is induced by the pressure at which the charge transfer begins in NiPc(AsF6)0.5.
KeywordsPressure Dependence Interband Transition Plasmon Absorption Counter Anion Organic Conductor
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