Herein, we report for the first time the underlying mechanism of realizing a bipolar rectifier from a donor−σ−acceptor system (11-mercaptoundeca-2,4,8,10-tetraenenitrile) in a configuration where the spins of the magnetic electrodes are kept parallel. To find out the role of the σ bond on the unique spin polarized quantum transport properties, we have critically examined how a shift in the position of the σ bond in the same molecular skeleton can lead to the transformation of a bipolar rectifier to a unipolar one. It has also been noticed that the addition of another σ bond in the said molecular skeleton can change the transport properties further. In this case, the new device shows bias specific rectification in both the spin channels and in particular, the rectification ratio (42) associated with the down spin channel is appreciably high. Our analyses reveal that both the position and number of the σ bond can modify the relative abundance of the 2p-density of states of the individual carbon atoms near the Fermi level of the left and right side Fe (100) electrodes which actually is accountable for the realization of such interesting device characteristics. The projected device density of states, transmission spectra and transmission eigenstates also corroborate nicely with the present in-silico observation. All the calculations are performed with density functional theory based nonequilibrium Green functions technique.

中文翻译：

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供体-σ-受体体系不同衍生物的计算机模拟测试，以实现双极性和单极性自旋整流器

在这里，我们首次报告了在磁性电极的自旋为保持平行。为了找出σ键在独特的自旋极化量子输运特性中的作用，我们已严格研究了σ键在同一分子骨架中的位置偏移如何导致双极性整流器转变为单极性整流器。 。还已经注意到，在所述分子骨架中添加另一个σ键可以进一步改变传输性质。在这种情况下，新设备在两个自旋通道中都显示特定于偏置的整流，尤其是整流比（42与向下旋转通道相关联的）明显较高。我们的分析表明，σ键的位置和数量均可以改变左侧和右侧Fe（100）电极费米能级附近各个碳原子2p态的相对丰度，这实际上是造成这种情况的原因实现这种有趣的设备特性。态，透射光谱和透射本征态的预计器件密度也与当前的电子观测相符。所有计算均基于基于密度泛函理论的非平衡格林函数技术进行。