Tunneling rates in electron transport through double-barrier molecular junctions in a scanning tunneling microscope

Tunneling rates in electron transport through double-barrier molecular junctions in a scanning tunneling microscope.

The scanning tunneling microscope enables atomic-scale measurements of electron transport through individual molecules. Copper phthalocyanine and magnesium porphine molecules adsorbed on a thin oxide film grown on the NiAl(110) surface were probed. The single-molecule junctions contained two tunneling barriers, vacuum gap, and oxide film. Differential conductance spectroscopy shows that electro...

Scanning tunneling spectroscopy of Cl vacancies in NaCl films: strong electron-phonon coupling in double-barrier tunneling junctions.

Broad Gaussian line shapes are observed in scanning tunneling spectroscopy of single, localized electronic states induced by Cl vacancies in ultrathin NaCl films on Cu surfaces. Using a simple inelastic resonance tunneling model, we show that the observed broad line shapes are caused by a strong coupling between the localized state and the optical phonons in the film. The parameters for the mod...

Coherent Tunneling Transport in Molecular Junctions†

Using saturated alkyl chain series with a dithiol anchor group, we systematically examined the intrinsic charge transport of single-molecule junctions in an electromigrated nanogap electrode. The saturated alkyl molecular system constitutes an important control series in molecular transport experiments to corroborate valid molecular junctions, because molecular energy levels remain nearly uncha...

Simulating Scanning Tunneling Microscope

Tunneling in double barrier junctions with "hot spots".

We investigate electronic transport in epitaxial Fe(100)/MgO/Fe/MgO/Fe double magnetic tunnel junctions with soft barrier breakdown (hot spots). Specificity of these junctions is continuous middle layer and nitrogen doping of the MgO barriers which provides soft breakdown at biases about 0.5 V. In the junctions with hot spots we observe quasiperiodic changes in the resistance as a function of b...