The quantum Hall effect can be substantially affected by interfacial coupling between the host two-dimensional electron gases and the substrate, and has been predicted to give rise to exotic topological states. Yet the understanding of the underlying physics and the controllable engineering of this interaction remains challenging. Here we demonstrate the observation of an unusual quantum Hall effect, which differs markedly from that of the known picture, in graphene samples in contact with an antiferromagnetic insulator CrOCl equipped with dual gates. Two distinct quantum Hall phases are developed, with the Landau levels in monolayer graphene remaining intact at the conventional phase, but largely distorted for the interfacial-coupling phase. The latter quantum Hall phase is even present close to the absence of a magnetic field, with the consequential Landau quantization following a parabolic relation between the displacement field and the magnetic field. This characteristic prevails up to 100 K in a wide effective doping range from 0 to 10¹³ cm⁻².

主体二维电子气和衬底之间的界面耦合会显着影响量子霍尔效应，并且预计会产生奇异的拓扑状态。然而，对这种相互作用的基础物理学和可控工程的理解仍然具有挑战性。在这里，我们展示了在与配备双门的反铁磁绝缘体 CrOCl 接触的石墨烯样品中观察到一种不寻常的量子霍尔效应，这与已知图片明显不同。开发了两个不同的量子霍尔相，单层石墨烯中的 Landau 能级在常规相中保持完整，但在界面耦合相中发生了很大程度的扭曲。后一个量子霍尔相甚至在接近没有磁场的情况下存在，随之而来的 Landau 量化遵循位移场和磁场之间的抛物线关系。这种特性在 0 到 10 的宽有效掺杂范围内高达 100 K¹³ 厘米^-2。