Effects Of The Interfacial Structure On Electron Transport Properties Of Molecular Junctions

Using density functional theory combined with non-equilibrium Green’s functions, this paper investigates the effect of the metal surface reconstruction or adsorbed cluster induced by adsorption of C60 molecules on electron transport properties of molecular devices.The following is the main content:1. The effects of surface reconstruction induced by C6o on electron transport. In experiments, a 7-atom-missing hole per (4×4) Cu(111) cell could be formed when C60 molecules grow on Cu(111) substrate. In terms of molecular devices constructed by C60 molecues and Cu(111) electrodes, the results indicate that surface reconstruction induces an increase of more than 50% in the current at low bias. Our current work suggests that surface reconstruction enhances the ability of conducting and could play a very important role in the electron transport properties.2. The effects of adsorbed clusters on electron transport. When preparing molecular junctions in experiment, especially in molecular self-assembly process, atom clusters or island structures may be adsorbed on the metal surface. We construct two-terminal systems with C6o molecule and Ni(111) electrodes. Then we study electron transport properties with the increase of the atom number N of clusters when magnetic moments of the two electrodes are parallel. Under the same bias, the results show that the current increases and their spin polarization rate decreases with the increase of N, which clarifies the importance of cluster size on the spin transport properties.