Degeneracies in multilayer graphene, including spin, valley, and layer degrees of freedom, can be lifted by Coulomb interactions, resulting in rich broken-symmetry states. Here, we report a ferromagnetic state in charge-neutral ABCA-tetralayer graphene driven by proximity-induced spin-orbit coupling from adjacent tungsten diselenide. The ferromagnetic state is identified as a Chern insulator with a Chern number of 4; its maximum Hall resistance reaches 78% quantization at zero magnetic field and is fully quantized at either 0.4 or –1.5 tesla. Three distinct broken-symmetry insulating states, layer-antiferromagnet, Chern insulator, and layer-polarized insulator, along with their transitions, can be continuously tuned by the vertical displacement field. In this system, the magnetic order of the Chern insulator can be switched by three knobs, including magnetic field, electrical doping, and vertical displacement field.

中文翻译：

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利用自旋轨道耦合观察晶体 ABCA-四层石墨烯中的陈绝缘体

多层石墨烯的简并性，包括自旋、谷和层自由度，可以通过库仑相互作用提升，从而产生丰富的破缺对称态。在这里，我们报告了由邻近二硒化钨的邻近感应自旋轨道耦合驱动的电荷中性 ABCA 四层石墨烯中的铁磁态。铁磁态被识别为陈绝缘体，陈数为4；其最大霍尔电阻在零磁场下达到 78% 量子化，并在 0.4 或 –1.5 特斯拉时完全量子化。三种不同的破缺对称绝缘态，层反铁磁体、陈绝缘体和层极化绝缘体，以及它们的转变，可以通过垂直位移场连续调节。在该系统中，陈绝缘体的磁序可以通过三个旋钮进行切换，包括磁场、电掺杂和垂直位移场。