Hund and pair-hopping signature in transport properties of degenerate nanoscale devices

TL;DR

This paper explores how Hund exchange and pair hopping influence transport in double-orbital nanoscale devices, revealing their signatures in stability diagrams, spectral weight transfer, and low-temperature phenomena like Kondo effects.

Contribution

It provides a detailed analysis of Coulomb interaction effects, emphasizing the importance of including Hund and pair-hopping terms for accurate experimental interpretation.

Findings

Hund exchange affects inelastic cotunneling and Kondo conductance.

Spectral weight transfer impacts charge current under gate and bias voltages.

Crude models with partial Coulomb interaction can mislead experimental analysis.

Abstract

We investigate the signature of a complete Coulomb interaction in transport properties of double-orbital nanoscale devices. We analyze the specific effects of Hund exchange and pair hopping terms, calculating in particular stability diagrams. It turns out that a crude model, with partial Coulomb interaction, may lead to a misinterpretation of experiments. In addition, it is shown that spectral weight transfers induced by gate and bias voltages strongly influence charge current. The low temperature regime is also investigated, displaying inelastic cotunneling associated with the exchange term, as well as Kondo conductance enhancement.