Molecular signature of highly conductive metal-molecule-metal junctions

Abstract

The simplicity of single-molecule junctions based on direct bonding of a small molecule between two metallic electrodes makes them an ideal system for the study of fundamental questions related to molecular electronics. Here we study the conductance properties of six different types of molecules by suspending individual molecules between Pt electrodes. All the molecular junctions show a typical conductance of about 1G 0 which is ascribed to the dominant role of the Pt contacts. However, despite the metalliclike conductivity, the individual molecular signature is well expressed by the effect of molecular vibrations in the inelastic contribution to the conductance.

Effects of bonding type and interface geometry on coherent transport through the single-molecule magnetMn12

“…In addition, recent experiments show that conductance through molecular junctions based on small single molecules can be enhanced to an order of G 0 by their direct bonding to the electrodes without a thiol group or any other linker molecules. 27,28 This enhancement is attributed to a strong coupling between the molecules and the electrodes, which places the transport in the transparent regime rather than in the tunneling regime. 28,29 However, corresponding systematic studies have not yet been carried out for electron transport through an SMM.…”

“…27,28 This enhancement is attributed to a strong coupling between the molecules and the electrodes, which places the transport in the transparent regime rather than in the tunneling regime. 28,29 However, corresponding systematic studies have not yet been carried out for electron transport through an SMM. In the case of quantum dots, the properties of interfaces are negligible in transport.…”

“…20,[22][23][24]27,28 Thus, in transport experiments, for a given bonding type, several binding sites are plausible, and hundreds of fabricated samples of the bonding type give rise to a histogram of conductance for given gate voltage or a series of current-voltage curves. In the present study, we take into account five different bonding types between an Mn 12 and Au electrodes, and for each bonding type, some representative interface geometries are examined.…”

Surveying Molecular Vibrations during the Formation of Metal−Molecule Nanocontacts

“…Despite the continuous progress, the electron conductance measured using either a scanning tunneling microscope (STM) or a break-junction device [6][7][8][9][10][11][12][13] has so far not elucidated this question clearly. The strength of the metal-molecule coupling, and in particular its variation during the contact formation, can be characterized through the spectroscopic signal of the molecular vibrations as measured by inelastic electron tunneling spectroscopy (IETS).…”

“…The strength of the metal-molecule coupling, and in particular its variation during the contact formation, can be characterized through the spectroscopic signal of the molecular vibrations as measured by inelastic electron tunneling spectroscopy (IETS). 6,9,[14][15][16][17] This can be recorded as a function of the tip-molecule distance allowing understanding to which extent the contact formation influences the molecular properties.A good molecular prototype to study the influence of the metal bond is carbon monoxide (CO). Indeed, this molecule is used as ligand to contact metal atoms in coordination chemistry and its electronic and vibration properties are very sensitive to the local adsorption environment.…”