Meron ground states of quantum Hall droplets

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.Comment: 6 pages, 6 figure

Structure of spinful quantum Hall states: A squeezing perspective

“…There are, in principle, several routes that one might take, but we found that only one of them correctly generates all the ground states of the model Hamiltonians, including the quasiholes states. Prior work [21][22][23][24] has mostly focused on the Halperin 25 or Haldane-Rezayi 26 states. We show that this concept can be extended to other known states such as the non-abelian spin singlet or spin-charge separation states, but can also provide a way to obtain new interesting states.…”

Direct Observation of Unconventional Topological Spin Structure in Coupled Magnetic Discs

“…There have also been several theoretical predictions regarding the existence of merons in condensed matter systems, e.g. as ground states in quantum Hall droplets [12,13], or thin chiral magnetic films [14], although the experimental verification is still lacking.…”

Chiral spin currents and spectroscopically accessible single merons in quantum dots

“…These spin textures are plotted using the real-space wave functions of the 2D harmonic trap. 22 Previous work [14][15][16] has focused on lowest-Landau-level physics or on semiclassical approximations. The present numerically exact results show that merons can exist far beyond the semiclassical regime; right down to the extreme quantum limit of very few confined particles where correlations are strongest.…”

“…A semiclassical (SC) ansatz for a single meron in a quantum Hall droplet is given in Ref. 16 2. (Color online) Two of the four meron textures for the three-particle states given in Eq. (8).…”

“…Recent literature predicts the formation of merons in confined systems such as QDs in large magnetic fields. [14][15][16] In this work, we use configuration-interaction techniques to study a fully interacting QD system to provide conclusive evidence for the formation of merons in the ground state. We find that merons form in systems containing as few as three particles, 17 at magnetic fields as low as 0.2 T, and away from the maximum density droplet regime.…”