Singlet-triplet transition in a lateral quantum dot

TL;DR

This paper investigates how the singlet-triplet transition in a lateral quantum dot affects electron transport, revealing a conductance maximum during the crossover influenced by exchange interactions and external magnetic fields.

Contribution

It provides a detailed analysis of the conductance behavior near the singlet-triplet transition, highlighting the effects of exchange interactions and magnetic fields on the transition's broadening.

Findings

Conductance peaks at the singlet-triplet crossover

Maximum conductance occurs at zero temperature and magnetic field

Zeeman splitting reduces the conductance maximum and increases background conductance

Abstract

We study transport through a lateral quantum dot in the vicinity of the singlet-triplet transition in its ground state. This transition, being sharp in an isolated dot, is broadened to a crossover by the exchange interaction of the dot electrons with the conduction electrons in the leads. For a generic set of system's parameters, the linear conductance has a maximum in the crossover region. At zero temperature and magnetic field, the maximum is the strongest. It becomes less pronounced at finite Zeeman splitting, which leads to an increase of the background conductance and a decrease of the conductance in the maximum.