Temperature dependent conductances of deformable molecular devices

TL;DR

This paper investigates how temperature influences electrical and thermal conductances in deformable molecular devices, revealing temperature-induced conductance steps, Franck-Condon effects, and Wiedemann-Franz law violations, with implications for experimental observations.

Contribution

It provides a non-perturbative analysis of temperature-dependent conductances in vibrationally coupled molecular devices using the Yu-Anderson model.

Findings

Conductances show a step from T=0 to half as temperature increases.

Spectral functions display Franck-Condon multiphonon steps.

Wiedemann-Franz law holds at low and high temperatures, but not in between.

Abstract

Transport through a molecular device coupled to a vibrational mode is studied. By mapping it to the Yu-Anderson model in the large contact broadening limit, the zero bias electric and heat conductances are evaluated non-perturbatively. These exhibit a step from their T=0 value to half of its value as T increases due to the opening of the inelastic scattering channel. The spectral function exhibits the Franck-Condon suppressed multiphonon steps. The Wiedemann-Franz law is satisfied at low and high temperatures, but is violated in between. Relations to experiments are discussed.