原位受控屏蔽对分数量子霍尔效应与复合费米子输运的影响
Impact of in-situ controlled disorder screening on fractional quantum Hall effects and composite-fermion transport
AI总结：
利用双栅GaAs量子阱原位调控远程杂质屏蔽，研究揭示了无序展宽与$ν=1/2$复合费米子电阻率的关联，并分离出背景杂质贡献。
摘要：
我们研究了由远程杂质（RIs）引起的随机势及其原位受控屏蔽对朗道能级填充因子$ν=1/2$附近分数量子霍尔效应（FQHEs）的影响。该实验通过使用双栅GaAs量子阱（QW）得以实现，这种结构允许独立控制QW中二维电子系统的密度$n_e$以及调制掺杂超晶格中过剩电子的密度（$n_\ ext{SL}$）。在固定$n_e$下，随着通过降低$n_\ ext{SL}$而减弱屏蔽，我们观察到由热激活推导的FQHEs表观能隙减小，这表明复合费米子（CFs）的无序展宽$Γ$相应增加。有趣的是，$Γ$的增加伴随着$ν=1/2$处纵向电阻率（$ρ_{1/2}$）的显著上升，而且其与$Γ$的相关性远强于电子迁移率$μ$与$Γ$的相关性。对RI屏蔽的原位控制使我们能够区分RIs和背景杂质（BIs）对$ρ_{1/2}$的贡献，其中后者与CF理论高度吻合。我们构建了一幅标度图，有助于在给定$n_e$和$μ$的条件下估算BIs对$ρ_{1/2}$的贡献。
英文摘要：
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 $ν= 1/2$. The experiment is made possible by using a dual-gate GaAs quantum well (QW) that allows for the independent control of the density $n_{e}$ of the two-dimensional electron system in the QW and that ($n_\text{SL}$) of excess electrons in the modulation-doping superlattice. As the screening is reduced by decreasing $n_\text{SL}$ at a fixed $n_{e}$, 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 $Γ$ of composite fermions (CFs). Interestingly, the increase in $Γ$ is accompanied by a noticeable increase in the longitudinal resistivity at $ν= 1/2$ ($ρ_{1/2}$), with a much stronger correlation with $Γ$ than electron mobility $μ$ has. The in-situ control of RI screening enables us to disentangle the contributions of RIs and background impurities (BIs) to $ρ_{1/2}$, with the latter in good agreement with the CF theory. We construct a scaling plot that helps in estimating the BI contribution to $ρ_{1/2}$ for a given set of $n_{e}$ and $μ$.
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