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<p>Low carrier densities in semimetals enable the exploration of magnetotransport in the quantum limit. Recent findings consistent with 3D quasi-quantum Hall effect (QQHE) have positioned semimetals as promising platforms for exploring 3D quantum Hall-like transport, but the lack of tunability in the Fermi level has limited QQHE observation. Here, we show how achieving ultralow carrier densities in the Dirac semimetal Cd<sub>3</sub>As<sub>2</sub> (&#xa0;~&#xa0;10<sup>16</sup> cm<sup>−3</sup>) can reveal QQHE signals at modest fields. At these low densities where QQHE is most accessible, we find that clear QQHE is obscured by charged disorder, which broadens Landau bands, scatters carriers, and affects quasi-quantization. Clear observation of QQHE in semimetals depends on Fermi level and disorder potential magnitudes. As theoretically predicted, Coulomb disorder is an essential ingredient for understanding the magnetoresistivity for a spectrum of Fermi levels in Cd<sub>3</sub>As<sub>2</sub>, anchoring the role of charged disorder in topological semimetal applications. We discuss future constraints and opportunities in exploring 3D QQHE in semimetals.</p>

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Interplay of quasi-quantum Hall effect and Coulomb disorder in semimetals

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月24日

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  • Ian A. Leahy,
  • Anthony D. Rice,
  • Jocienne N. Nelson,
  • Herve Ness,
  • Mark van Schilfgaarde,
  • David Graf,
  • Alexey Suslov,
  • Wei Pan,
  • Kirstin Alberi

摘要

Low carrier densities in semimetals enable the exploration of magnetotransport in the quantum limit. Recent findings consistent with 3D quasi-quantum Hall effect (QQHE) have positioned semimetals as promising platforms for exploring 3D quantum Hall-like transport, but the lack of tunability in the Fermi level has limited QQHE observation. Here, we show how achieving ultralow carrier densities in the Dirac semimetal Cd3As2 ( ~ 1016 cm−3) can reveal QQHE signals at modest fields. At these low densities where QQHE is most accessible, we find that clear QQHE is obscured by charged disorder, which broadens Landau bands, scatters carriers, and affects quasi-quantization. Clear observation of QQHE in semimetals depends on Fermi level and disorder potential magnitudes. As theoretically predicted, Coulomb disorder is an essential ingredient for understanding the magnetoresistivity for a spectrum of Fermi levels in Cd3As2, anchoring the role of charged disorder in topological semimetal applications. We discuss future constraints and opportunities in exploring 3D QQHE in semimetals.