English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We revisit the theory of the collective neutral excitation mode in thefractional quantum Hall effect at Landau level filling fractions $\nu=1/3$ and$\nu=7/3$. We include the effect of finite thickness of the two-dimensionalelectron gas and use extensive exact diagonalizations in the torus geometry. Inthe lowest Landau level the collective gapped mode i.e. the magnetoroton alwaysmerges in the continuum in the long-wavelength limit. In the second Landaulevel the mode is well-defined only for wavevectors smaller than a criticalvalue and disappears in the continuum beyond this point. Its curvature nearzero momentum is opposite to that of the LLL. It is well separated from thecontinuum even at zero momentum and the gap of the continuum of higher-lyingstates is twice the collective mode gap at $k=0$. The shape of the dispersionrelation survives a perturbative treatment of Landau level mixing.

Shape of the magnetoroton at $\nu=1/3$ and $\nu=7/3$ in real samples