# Spin fluctuations in the 0.7-anomaly in quantum point contacts

## TL;DR

This paper investigates how spin fluctuations related to the van Hove ridge influence the 0.7 anomaly in quantum point contacts, revealing effects on conductance, spin susceptibility, and traversal time.

## Contribution

It provides a detailed analysis of the impact of density of states enhancements on dynamical properties in QPCs, linking spin fluctuations to the 0.7 anomaly.

## Key findings

- Temperature dependence of conductance matches experiments
- Enhanced spin susceptibility due to van Hove ridge effects
- Lengthened traversal time indicating slow spin fluctuations

## Abstract

It has been argued that the 0.7 anomaly in quantum point contacts (QPCs) is due to an enhanced density of states at the top of the QPC-barrier (van Hove ridge), which strongly enhances the effects of interactions. Here, we analyze their effect on dynamical quantities. We find that they pin the van Hove ridge to the chemical potential when the QPC is subopen; cause a temperature dependence for the linear conductance that qualitatively agrees with experiment; strongly enhance the magnitude of the dynamical spin susceptibility; and significantly lengthen the QPC traversal time. We conclude that electrons traverse the QPC via a slowly fluctuating spin structure of finite spatial extent.