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The spin transport in ferrocene molecules has been examined by using the nonequilibrium Green’s function formalism with density functional theory. The ferrocene molecules were sandwiched between the two nickel electrodes in a parallel magnetic configuration, which enhanced the current in comparison with that in an antiparallel spin state and resulting in tunnel magnetoresistance (TMR). The current, having an opposite spin state to that of the ferromagnetic electrode, was the main channel for electron transport. In addition, it became clear that ferrocenylene molecules, having a fulvalene structure with an extended π-conjugation, enhanced the TMR effect. [ABSTRACT FROM AUTHOR]

The main block of polyferrocenylsilane (PFS) polymer is composed of ferrocene molecules bridged by silicon atoms. In this study, we found that PFS was insoluble in an imidazolium-based ionic liquid. On the other hand, PFS dissolved easily in an ionic liquid based on pyrazolium, under ordinary conditions and at room temperature. Furthermore, dissolving PFS in this ionic liquid afforded a p-type doped material. We found that the secondary amine in pyrazolium acted as an oxidant for ferrocene, allowing the PFS to dissolve in the ionic liquid. The measured thermal properties of the PFS-ionic liquids allowed us to show the existence of an attractive interaction between PFS and the ionic liquid. [ABSTRACT FROM AUTHOR]

We focused on the spin transport properties of polymers containing ferrocene and the related transition-metal-benzene sandwich compound (metal = Cr and V) with a silicon bridge such as poly(ferrocenylsilane) and poly(metalarenylsilane). As a model system, a sulfur-substituted oligomer was put on gold electrodes via the sulfur-gold interaction. Spin transport between the two gold electrodes was calculated using a non-equilibrium Green's function formalism and density functional theory. We have found that the oligomer containing Cr or V atoms exhibited an almost perfect spin filter behavior in which all the 3dz2 orbitals contributed to the electron transport. [ABSTRACT FROM AUTHOR]

Abstract: The electronic structures of ferrocene-containing polymers with heteroatom-bridges have been examined using the tight-binding crystal orbital method. The relationship between the band structures of the polymers and their bridging moieties was examined. The highest occupied (HO) band of the polymers with saturated carbon-bridges consisted of π-type p orbitals of cyclopentadienyl ring. On the other hand, the polymers with silicon-bridges possessed a localised HO band, which was formed by orbitals of iron atom. [Copyright &y& Elsevier]

Abstract: Electronic structures of polymers, ferrocene (Cp2Fe, Cp=η5-C5H5) in the main chain, were examined using the tight-binding crystal orbital method. Attention was focused on the manner in which the band structures of the polymers were influenced by the bridging moieties between the ferrocenes. Ferrocene-containing polymers with unsaturated carbon bridges possessed relatively wide bandwidths of both the highest occupied band and the lowest unoccupied band. Although the π conjugation was broken at the iron atoms, the unsaturated carbon bridges could form limited delocalization of the π electrons between the neighbouring Cp rings via the bridging moieties. [Copyright &y& Elsevier]

I present a theoretical study of the electronic transport properties of nickelocenylferrocene sandwiched between gold electrodes. Compared with the biferrocene system, the nickelocenylferrocene system had high electrical conduction and rectification in the bias range -1 to 1 V. Furthermore, the spin-down states of the nickelocenylferrocene system exhibited perfect spin-filtering properties. From the electronic states of the nickelocenylferrocene, it was found that the rectification was caused by a difference in the bias-dependent behaviors between the Fe 3d and Ni 3d orbitals. [ABSTRACT FROM AUTHOR]