Spin-droplets in confined quantum Hall systems

TL;DR

This paper investigates the formation of incompressible spin-droplets in confined quantum Hall systems, revealing their emergence at specific filling factors and their potential link to the fragility of certain quantum Hall states.

Contribution

It provides both theoretical and experimental evidence of spin-droplet formation in quantum dots, proposing a finite-geometry alternative to bulk quantum Hall states.

Findings

Spin-droplets form on the highest Landau level for N>30 electrons.

Onset of spin-droplet regime at filling factor v=5/2.

Spin-droplet formation may explain the fragility of v=5/2 state in narrow contacts.

Abstract

Two-dimensional semiconductor quantum dots are studied in the the filling-factor range 2<v<3. We find both theoretical and experimental evidence of a collective many-body phenomenon, where a fraction of the trapped electrons form an incompressible spin-droplet on the highest occupied Landau level. The phenomenon occurs only when the number of electrons in the quantum dot is larger than ~30. We find the onset of the spin-droplet regime at v=5/2. This proposes a finite-geometry alternative to the Moore-Read-type Pfaffian state of the bulk two-dimensional electron gas. Hence, the spin-droplet formation may be related to the observed fragility of the v=5/2 quantum Hall state in narrow quantum point contacts.