Meron ground states of quantum Hall droplets

TL;DR

This paper demonstrates that in finite quantum Hall systems, topological meron excitations can become the lowest energy states due to many-body correlations, especially when the gyromagnetic ratio is small, contrasting their behavior in infinite systems.

Contribution

It introduces mean field ansatzes for meron wave functions that enable analysis of larger systems and shows merons can be deconfined and energetically favorable in finite quantum Hall droplets.

Findings

Merons become deconfined in finite quantum Hall droplets.

Merons can be the lowest energy excitations when the gyromagnetic ratio is small.

Mean field ansatzes allow analysis of larger system sizes.

Abstract

We argue that topological meron excitations, which are in a strong coupling phase (bound in pairs) in infinite quantum Hall ferromagnets, become deconfined in finite size quantum Hall systems. Although effectively for larger systems meron energy grows with the size of the system, when gyromagnetic ratio is small meron becomes the lowest lying state of a quantum Hall droplet. This comes as a consequence of the many-body correlations built in the meron construction that minimize the interaction energy. We demonstrate this by using mean field ansatzes for meron wave function. The ansatzes will enable us to consider much larger system sizes than in the previous work [A. Petkovic and M.V. Milovanovic, PRL 98, 066808 (2007)], where fractionalization into merons was introduced.