Construction of Super-Structured Spin-Polarized Donor having Spin-rectifying Property

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The ultimate goal of this project is to construct super-structured "spin-polarized donors" that operate as molecule-based spin-rectifying devices. The following findings along this line have been achieved during the project period.1.In order to improve the conductivity of its ionradical salt of benzo-annulated OF based spin-polarized donors, sulfur atoms of the donor moiety were replaced with selenium atoms. The ionradical salts and the charge-transfer complexes of these spin-polarized donors were also prepared. Among them, an ion-radical salt of a selenium-introduced spin-polarized donor (ESBN) turned out to behave as the low band-gap (Ea = 40 meV) semiconductor, which exhibited the possibility to show the metallic conductivity under a high pressure. Such ion-radical salts are expected to manifest spin-alignment through the spin-polarized conduction electrons on the basis of the double exchange mechanism.2.A novel TTF based donor, OdTBN, having long alkyl chains was prepared to increa … More se the feasibility of fabrication. A thin film composed of OdTBN was formed on a silicon wafer and it was found that the sample acted as a field-effect transistor (FET).3.The preparative method of Roll nano-particles chemisorbed by organic π-radical has been established. The nano-particles, with an average diameter of 4nm, were chemisorbed by ca. 100 molecules of a thiol-derivatized spin-polarized donor, which was generated by the reduction cleavage of the corresponding disulfide precursor. The extreme broadening of ESR line-shape suggests the presence of the exchange interaction between localized spins of chemisorbed radicals and conduction electrons in the gold nano-particle. Moreover, it was to be noted that the evaluation technique of the precise size and its distribution of gold nano-particles by means of an X-ray small-angle-scattering method was established in collaboration with Rigaku-Denki Corporation.4.Various molecular wires bearing thiol groups at both ends were synthesized and it was found that they constructed network-like structures with gold nano-particles on interdigitated gold electrodes. The conducting property of the networked gold nano-particles strongly depended on the size of the nano-particles and the structure and the length of molecular wires. The conductivity of the networked structures was measured under the application of an external magnetic field and it was found that some of the samples exhibited a magneto-resistance effect. Less