Spin-polarized electron transport through selected molecules by means of spin-polarized scanning tunneling microscopy

我们的目的是确定自旋输运性质的有机分子和单分子薄膜的自旋极化扫描隧道显微镜和光谱在低温（4K）超高真空条件下。在超高真空条件下，可以在单晶表面制备金属有机分子膜。两类有机分子将被用作模型系统。在第一步骤中，非磁性Al-戊二酸盐将在铁磁衬底上生长。利用铁磁针尖，我们将研究分子-衬底系统的自旋分辨电子结构和电子从针尖通过分子到衬底的自旋相关输运。这些测量可以在从薄分子膜到单分子水平的尺度上进行。由此，将获得对金属有机分子中的自旋扩散的洞察。作为第二步，将使用含有过渡金属元素而不是Al的相同分子。我们将研究分子中金属原子的局域自旋对自旋输运性质的影响。由于自旋极化电流，可能会发生诸如增强的自旋散射、选择性自旋通道输运或自旋状态的修改之类的效应。金属-有机模型体系的实验所获得的知识可用于有机自旋电子学的应用。

Our aim is to determine the spin transport properties of films of organic molecules and single molecules by means of spin-polarized scanning tunneling microscopy and spectroscopy at low temperatures (4K) under ultra high vacuum conditions. Metal-organic molecular films will be prepared in ultra-high vacuum on single crystal surfaces. Two classes of organic molecules will be used as model systems. In a first step, non-magnetic Al-pentanedionate will be grown on ferromagnetic substrates. By using ferromagnetic tips we will study the spin-resolved electronic structure of the molecule-substrate system and the spin-dependent transport of electrons from the tip through the molecule to the substrate. These measurements can be performed on scales from thin molecular films down to the single molecule level. From this, insight in the spin diffusion in metal-organic molecules will be gained. As a second step, identical molecules containing transition metal elements instead of Al will be used. We will investigate the impact of the local spin of the metallic atom in the molecule on the spin transport properties. Effects like enhanced spin scattering, selective spin channel transport or modification of the spin state due to the spin-polarized currents may occur. The knowledge gained by the experiments on the metal-organic model systems can be used for applications in organic spintronics.