Tagami Katsunori, Tsukada Masaru
Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
J Phys Chem B. 2004 May 20;108(20):6441-4. doi: 10.1021/jp037953e.
The coherent quantum transport properties through the spin-polarized polyphenoxyl radical molecule have been investigated, using the density-functional-derived tight-binding model and the Green's functions method. The majority and minority spin components exhibit considerably different transmission spectra in the vicinity of the Fermi level. Namely, each spin component carries a different amount of current when the bias voltage is applied between the two electrodes that sandwich the polyradical molecule. Therefore, if the magnetization axis of the polyradical is fixed by the external magnetic field, and if the spin flip does not occur during the transmission, the assumed molecular bridge is expected to work as a spin filter or a spin valve. Furthermore, as long as the bias voltage is weak, the total spin current is observed to be larger than the current through its reduced molecular form. It indicates that the adsorption of some chemical species on the radical sites can be sensed by the change in conductance of the molecular bridge.
利用密度泛函导出的紧束缚模型和格林函数方法，研究了通过自旋极化的聚酚氧基自由基分子的相干量子输运性质。多数自旋和少数自旋分量在费米能级附近表现出显著不同的透射谱。也就是说，当在夹着多自由基分子的两个电极之间施加偏置电压时，每个自旋分量携带的电流不同。因此，如果多自由基的磁化轴由外部磁场固定，并且如果在传输过程中不发生自旋翻转，则假定的分子桥有望用作自旋过滤器或自旋阀。此外，只要偏置电压较弱，观察到总自旋电流大于通过其还原分子形式的电流。这表明自由基位点上某些化学物质的吸附可以通过分子桥电导的变化来感知。
