The realization of the quantum spin Hall effect in HgTe quantum wells has led to the development of topological materials, which, in combination with magnetism and superconductivity, are predicted to host chiral Majorana fermions. However, the large magnetization in conventional quantum anomalous Hall systems makes it challenging to induce superconductivity. Here, we report two different emergent quantum Hall effects in (Hg,Mn)Te quantum wells. First, a previously unidentified quantum Hall state emerges from the quantum spin Hall state at an exceptionally low magnetic field of ~50 mT. Second, tuning toward the bulk p-regime, we resolve quantum Hall plateaus at fields as low as 20 to 30 mT, where transport is dominated by a van Hove singularity in the valence band. These emergent quantum Hall phenomena rely critically on the topological band structure of HgTe, and their occurrence at very low fields makes them an ideal candidate for realizing chiral Majorana fermions.

HgTe量子阱中量子自旋霍尔效应的实现导致了拓扑材料的发展，该拓扑材料与磁性和超导性相结合，预计将容纳手性马约拉纳费米子。然而，常规量子异常霍尔系统中的大磁化强度使其难以诱导超导性。在这里，我们报道了（Hg，Mn）Te量子阱中两种不同的涌现量子霍尔效应。首先，在约50 mT的极低磁场下，量子自旋霍尔态出现了一个先前无法识别的量子霍尔态。二，向批量p调整-体制，我们解析低至20至30 mT的场的量子霍尔高原，其中运价由价带中的范霍夫奇异性主导。这些新兴的量子霍尔现象严重依赖于HgTe的拓扑带结构，并且它们在非常低的场中发生使它们成为实现手性马约拉那费米子的理想候选者。