2014/04/30 by Lena Simine, Dvira Segal
Chemistry · Engineering · Physics and Astronomy · #Advanced Physical and Chemical Molecular Interactions #Molecular Junctions and Nanostructures #Quantum and electron transport phenomena #cond-mat.mes-hall #physics.chem-ph
paper · pdf · doi:10.1063/1.4885051
published as J. Chem. Phys. 141, 014704 (2014)
arxiv created 2014/04/30 · openalex publication_date 2014/07/02 · arxiv updated 2014/07/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study electron transport in nanojunctions in which an electron on a quantum dot or a molecule is interacting with an N-state local impurity, a harmonic ("Holstein") mode, or a two-state system ("spin"). These two models, the Anderson-Holstein model and the spin-fermion model, can be conveniently transformed by a shift transformation into a form suitable for a perturbative expansion in the tunneling matrix element. We explore the current-voltage characteristics of the two models in the limit of high temperature and weak electron-metal coupling using a kinetic rate equation formalism, considering both the case of an equilibrated impurity, and the unequilibrated case. Specifically, we show that the analog of the Franck-Condon blockade physics is missing in the spin-fermion model. We complement this study by considering the low-temperature quantum adiabatic limit of the dissipative spin-fermion model, with fast tunneling electrons and a slow impurity. While a mean-field analysis of the Anderson-Holstein model suggests that nonlinear functionalities, bistability and hysteresis may develop, such effects are missing in the spin-fermion model at the mean-field level.