Crossover and Coexistence of Quasiparticle Excitations in the Fractional Quantum Hall Regime at $\nu \leq 1/3$

TL;DR

This study observes new low-energy excitations in the fractional quantum Hall regime at filling factors with $ u \, extless= \, 1/3$, revealing a transition in the quantum ground state associated with different quasiparticle excitations.

Contribution

It reports the first observation of coexisting $ u=p/( ext{ extphi} p \, extpm \, 1)$ excitations with distinct behaviors, indicating a quantum phase transition at $ u=1/3$ in the fractional quantum Hall regime.

Findings

Discovery of new low-lying excitations at $ u=p/( extphi p \, extpm \, 1)$ with $ extphi=4$

Coexistence of $ extphi=2$ and $ extphi=4$ excitations below $ u=1/3$

Abrupt emergence of new modes suggests a change in the quantum ground state

Abstract

New low-lying excitations are observed by inelastic light scattering at filling factors $\nu=p/(\phi p \pm 1)$ of the fractional quantum Hall regime with $\phi=4$. Coexisting with these modes throughout the range $\nu \leq 1/3$ are $\phi=2$ excitations seen at 1/3. Both $\phi=2$ and $\phi=4$ excitations have distinct behaviors with temperature and filling factor. The abrupt first appearance of the new modes in the low energy excitation spectrum at $\nu \lesssim 1/3$ suggests a marked change in the quantum ground state on crossing the $\phi=2 \to \phi=4$ boundary at $\nu = 1/3$.