Shot-Noise Signatures of 0.7 Structure and Spin in a Quantum Point Contact

TL;DR

This study investigates shot noise and conductance in a quantum point contact, revealing how spin and the 0.7 conductance anomaly influence noise signatures under varying magnetic fields.

Contribution

It provides the first detailed analysis linking shot noise asymmetries to the 0.7 conductance structure and spin effects in quantum point contacts.

Findings

Shot noise asymmetry correlates with the 0.7 conductance feature.

High magnetic fields produce symmetric spin-resolved noise signatures.

A phenomenological model accurately describes the observed phenomena.

Abstract

We report simultaneous measurement of shot noise and dc transport in a quantum point contact as a function of source-drain bias, gate voltage, and in-plane magnetic field. Shot noise at zero field exhibits an asymmetry related to the 0.7 structure in conductance. The asymmetry in noise evolves smoothly into the symmetric signature of spin-resolved electron transmission at high field. Comparison to a phenomenological model with density-dependent level splitting yields good quantitative agreement.