Correlation effects in bistability at the nanoscale: steady state and beyond

TL;DR

This paper investigates multistability in nanoscale junctions under bias using advanced theoretical methods, revealing how electron interactions influence steady states and how dynamical correlations can suppress bistability.

Contribution

It compares steady-state solutions and dynamics in different approximation levels, highlighting the role of electron correlations in bistability at the nanoscale.

Findings

Multiple steady-state solutions exist at the Hartree-Fock and ALDA levels.

Dynamical correlation effects can suppress bistability.

Switching between solutions can be achieved through time evolution.

Abstract

The possibility of finding multistability in the density and current of an interacting nanoscale junction coupled to semi-infinite leads is studied at various levels of approximation. The system is driven out of equilibrium by an external bias and the non-equilibrium properties are determined by real-time propagation using both time-dependent density functional theory (TDDFT) and many-body perturbation theory (MBPT). In TDDFT the exchange-correlation effects are described within a recently proposed adiabatic local density approximation (ALDA). In MBPT the electron-electron interaction is incorporated in a many-body self-energy which is then approximated at the Hartree-Fock (HF), second-Born (2B) and GW level. Assuming the existence of a steady-state and solving directly the steady-state equations we find multiple solutions in the HF approximation and within the ALDA. In these cases we investigate if and how these solutions can be reached through time evolution and how to reversibly switch between them. We further show that for the same cases the inclusion of dynamical correlation effects suppresses bistability.