Biomedical subjects

Karsten Flensberg

Publications and source records attributed to Karsten Flensberg.

3 recordsLinked to original sources

PubMed2006

Electron transfer dynamics of bistable single-molecule junctions.

We present transport measurements of single-molecule junctions bridged by a molecule with three benzene rings connected by two double bonds and with thiol end-groups that allow chemical binding to gold electrodes. The I-V curves show switching behavior between two distinct states. By statistical analysis of the switching events, we show that a 300 meV mode mediates the transition between the two states. We propose that breaking and reformation of a S-H bond in the contact zone between molecule and electrode explains the observed bistability.

Benzene↗

PubMed2005

Vibrational sidebands and the Kondo effect in molecular transistors.

Electron transport through molecular quantum dots coupled to a single vibrational mode is studied in the Kondo regime. We apply a generalized Schrieffer-Wolff transformation to determine the effective low-energy spin-spin-vibron interaction. From this model we calculate the nonlinear conductance and find Kondo sidebands located at bias voltages equal to multiples of the vibron frequency. Because of selection rules, the side peaks are found to have strong gate-voltage dependences, which can be tested experimentally. In the limit of weak electron-vibron coupling, we employ a perturbative renormalization group scheme to calculate analytically the nonlinear conductance.

Journal Article↗

PubMed2005

Weak Coulomb blockade effect in quantum dots.

We develop the general nonequilibrium theory of transport through a quantum dot, including Coulomb blockade effects via a 1/N expansion, where N is the number of scattering channels. At lowest order we recover the Landauer formula for the current plus a self-consistent equation for the dot potential. We obtain the leading corrections and compare with earlier approaches. Finally, we show that to leading and to next leading order in 1/N there is no interaction correction to the weak localization, in contrast to previous theories, but consistent with experiments by Huibers et al. [Phys. Rev. Lett. 81, 1917 (1998)], where N=4.

Journal Article↗