Fractional Quantum Hall Effect Energy Gaps: Role of Electron Layer Thickness

The fractional quantum Hall effect (FQHE) stands as a quintessential manifestation of an interacting two-dimensional electron system. One FQHE's most fundamental characteristics is the energy gap separating incompressible ground state from its excitations. Yet, despite nearly four decades investigations, quantitative agreement between theoretically calculated and experimentally measured gaps lacking. Here we report comparison available theoretical calculations that take into account role finite layer thickness Landau level mixing. Our systematic experimental study FQHE uses very high-quality systems confined to GaAs wells with varying well widths. All fall bellow calculations, but increases, results experiments come closer. Accounting for disorder in phenomenological manner, find be reasonable although some discrepancies remain.