Department of Chemical Physics, ‡Department of Materials and Interfaces, and §Department of Chemical Research Support, Weizmann Institute of Science , Rehovot, Israel.
Nano Lett. 2016 Mar 9;16(3):1741-5. doi: 10.1021/acs.nanolett.5b04674. Epub 2016 Feb 29.
Molecular junctions based on ferromagnetic electrodes allow the study of electronic spin transport near the limit of spintronics miniaturization. However, these junctions reveal moderate magnetoresistance that is sensitive to the orbital structure at their ferromagnet-molecule interfaces. The key structural parameters that should be controlled in order to gain high magnetoresistance have not been established, despite their importance for efficient manipulation of spin transport at the nanoscale. Here, we show that single-molecule junctions based on nickel electrodes and benzene molecules can yield a significant anisotropic magnetoresistance of up to ∼200% near the conductance quantum G0. The measured magnetoresistance is mechanically tuned by changing the distance between the electrodes, revealing a nonmonotonic response to junction elongation. These findings are ascribed with the aid of first-principles calculations to variations in the metal-molecule orientation that can be adjusted to obtain highly spin-selective orbital hybridization. Our results demonstrate the important role of geometrical considerations in determining the spin transport properties of metal-molecule interfaces.
基于铁磁电极的分子结允许在接近自旋电子学小型化极限的情况下研究电子自旋输运。然而，这些结表现出中等的磁电阻，其对铁磁体-分子界面的轨道结构敏感。尽管对于在纳米尺度上有效操纵自旋输运很重要，但尚未确定为获得高磁电阻应该控制的关键结构参数。在这里，我们表明基于镍电极和苯分子的单分子结在电导量子 G0 附近可产生高达约 200%的显著各向异性磁电阻。通过改变电极之间的距离可以对测量得到的磁电阻进行机械调谐，从而揭示出与结伸长的非单调响应。借助第一性原理计算将这些发现归因于金属-分子取向的变化，这种变化可以进行调整以获得高度自旋选择性的轨道杂化。我们的结果表明，在确定金属-分子界面的自旋输运性质时，几何考虑因素起着重要作用。
