American Physical Society
Atomic-Scale Control of Electron Transport
through Single Molecules
Y. F. Wang, J. Kröger, R. Berndt,
H. Vázquez, M. Brandbyge, and M. Paulsson
Phys. Rev. Lett. 104, 176802
(Published April 27, 2010)
Illustration: W. F. Wang et al.,
Phys. Rev. Lett. (2010)
Electron transport through molecules has implications for a range of subjects. In
particular, conductance through single-molecule junctions is known to have a complex
dependence on atomic structure, orientation, and bonding properties. However,
investigations with atomic-scale control of the junction geometry are scarce.
In their paper in Physical Review Letters, Yongfeng Wang and collaborators from
Germany, Denmark, and Sweden demonstrate that the conductance in a singlemolecule junction varies over orders of magnitude.
Wang et al. present scanning tunneling microscopy measurements of the conductance
of tin-phthalocyanine (SnPc) adsorbed on a Ag(111) surface in contact with a tungsten
tip covered with silver. By manipulating the chemical bonding between SnPc and
Ag(111) through selective dehydrogenation of SnPc and an atomic-scale structuring of
the electrode, the conductance of single-molecule junctions is varied from 0.013 to
0.32 in units of the quantum of conductance. The authors also perform ab initio
calculations combined with a nonequilibrium Green’s function technique for a
quantitative analysis of the electron transport through Ag-SnPc-Ag junctions. This
opens an avenue to study current flow through single molecules by combining
transport measurements with atomic manipulation capabilities of the scanning
tunneling microscope. – Sarma Kancharla