Strong spin-filtering and spin-valve effects in a molecular V-C(60)-V contact

The impact of Fe atom on the spin-filter and spin thermoelectric properties of Au-Fe@C20-Au monomer and dimer systems

Based on density functional theory and non-equilibrium Green's function formalism, we explore the effect of Fe atom in Au-Fe@C20-Au monomer and dimer systems in comparison with the C20 fullerene molecular junctions. We calculate the spin-dependent transmission coefficient, spin polarization and also their spin thermoelectric coefficients to investigate magnetic properties in the system. Our results indicate that the presence of Fe atoms enhances substantially the spin-filter and increases the spin figure of merit in the dimer system. We suggest that the Au-(Fe@C20)2-Au system is a suitable junction for designing spin-filtering and spin thermoelectric devices and eventually it is a good candidate for spintronic applications.

Stable Au-C bonds to the substrate for fullerene-based nanostructures

We report on the formation of fullerene-derived nanostructures on Au(111) at room temperature and under UHV conditions. After low-energy ion sputtering of fullerene films deposited on Au(111), bright spots appear at the herringbone corner sites when measured using a scanning tunneling microscope. These features are stable at room temperature against diffusion on the surface. We carry out DFT calculations of fullerene molecules having one missing carbon atom to simulate the vacancies in the molecules resulting from the sputtering process. These modified fullerenes have an adsorption energy on the Au(111) surface that is 1.6 eV higher than that of C60 molecules. This increased binding energy arises from the saturation by the Au surface of the bonds around the molecular vacancy defect. We therefore interpret the observed features as adsorbed fullerene-derived molecules with C vacancies. This provides a pathway for the formation of fullerene-based nanostructures on Au at room temperature.

Chemical control of electrical contact to sp² carbon atoms

Carbon-based nanostructures are attracting tremendous interest as components in ultrafast electronics and optoelectronics. The electrical interfaces to these structures play a crucial role for the electron transport, but the lack of control at the atomic scale can hamper device functionality and integration into operating circuitry. Here we study a prototype carbon-based molecular junction consisting of a single C₆₀ molecule and probe how the electric current through the junction depends on the chemical nature of the foremost electrode atom in contact with the molecule. We find that the efficiency of charge injection to a C₆₀ molecule varies substantially for the considered metallic species, and demonstrate that the relative strength of the metal-C bond can be extracted from our transport measurements. Our study further suggests that a single-C₆₀ junction is a basic model to explore the properties of electrical contacts to meso- and macroscopic sp² carbon structures.

Understanding metal-molecule contacts is crucial for molecular electronic devices. Here, the authors use a C60-terminated scanning tunnelling tip to probe how the chemical nature of the contacting atom on the substrate electrode determines the transport properties.