Ultra-high-quality two-dimensional electron systems

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 x 10(6) cm(2) V-1 s(-1) at an electron density of 2.0 x 10(11) cm(-2). These results imply only 1 residual impurity for every 10(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 (Delta) of the fractional quantum Hall state at the Landau-level filling (nu) = 5/2, which is widely believed to be non-Abelian and of potential use for topological quantum computing, reaches Delta approximate to 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. Source-material purification and optimized vacuum chamber design lead to a breakthrough in GaAs sample quality.

Automated summary

By improving sample quality and innovating materials and vacuum chamber design, researchers have achieved a breakthrough in GaAs quantum well systems with two-dimensional electrons, demonstrating high mobility and low residual impurities.