Chung Yoon Jang, Villegas Rosales K A, Baldwin K W, Madathil P T, West K W, Shayegan M, Pfeiffer L N
Department of Electrical Engineering, Princeton University, Princeton, NJ, USA.
Nat Mater. 2021 May;20(5):632-637. doi: 10.1038/s41563-021-00942-3. Epub 2021 Feb 25.
Two-dimensional electrons confined to GaAs quantum wells are hallmark platforms for probing electron-electron interactions. Many key observations have been made in these systems as sample quality has improved over the years. Here, we present a breakthrough in sample quality via source-material purification and innovation in GaAs molecular beam epitaxy vacuum chamber design. Our samples display an ultra-high mobility of 44 × 10 cm V s at an electron density of 2.0 × 10 cm. These results imply only 1 residual impurity for every 10 Ga/As atoms. The impact of such low impurity concentration is manifold. Robust stripe and bubble phases are observed, and several new fractional quantum Hall states emerge. Furthermore, the activation gap (Δ) of the fractional quantum Hall state at the Landau-level filling (ν) = 5/2, which is widely believed to be non-Abelian and of potential use for topological quantum computing, reaches Δ ≈ 820 mK. We expect that our results will stimulate further research on interaction-driven physics in a two-dimensional setting and substantially advance the field.
限制在砷化镓量子阱中的二维电子是探测电子-电子相互作用的标志性平台。随着这些年来样品质量的提高，在这些系统中已经取得了许多关键观测结果。在此，我们通过源材料纯化和砷化镓分子束外延真空腔设计的创新实现了样品质量的突破。我们的样品在电子密度为2.0×10¹⁵cm⁻²时显示出44×10⁶cm²V⁻¹s⁻¹的超高迁移率。这些结果意味着每10⁶个镓/砷原子中只有1个残余杂质。如此低的杂质浓度产生了多方面的影响。观察到了稳健的条纹相和泡状相，并且出现了几个新的分数量子霍尔态。此外，朗道能级填充（ν）= 5/2时的分数量子霍尔态的激活能隙（Δ）达到Δ≈820 mK，人们普遍认为它是非阿贝尔的，并且在拓扑量子计算中有潜在用途。我们预计我们的结果将激发对二维环境中相互作用驱动物理的进一步研究，并极大地推动该领域的发展。
