Abstract
We examine the impact of random potential due to remote impurites (RIs) and its in situ controlled screening on fractional quantum Hall effects (FQHEs) around Landau-level filling factor . The experiment is made possible by using a dual-gate GaAs quantum well (QW) that allows for the independent control of the density of the two-dimensional electron system in the QW and that () of excess electrons in the modulation-doping superlattice. As the screening is reduced by decreasing at a fixed , we observe a decrease in the apparent energy gap of the FQHEs deduced from thermal activation, which signifies a corresponding increase in the disorder broadening of composite fermions (CFs). Interestingly, the increase in is accompanied by a noticeable increase in the longitudinal resistivity at (), with a much stronger correlation with than electron mobility has. The in situ control of RI screening enables us to disentangle the contributions of RIs and background impurities (BIs) to with the latter in good agreement with the CF theory. We construct a scaling plot that helps in estimating the BI contribution to for a given set of and .
- Received 22 March 2022
- Revised 27 May 2022
- Accepted 22 July 2022
DOI:https://doi.org/10.1103/PhysRevB.106.075302
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