The atomic thickness of two-dimensional materials provides a unique opportunity to control their electrical¹ and optical² properties as well as to drive the electronic phase transitions³ by electrostatic doping. The discovery of two-dimensional magnetic materials^{4,5,6,7,8,9,10} has opened up the prospect of the electrical control of magnetism and the realization of new functional devices¹¹. A recent experiment based on the linear magneto-electric effect has demonstrated control of the magnetic order in bilayer CrI₃ by electric fields¹². However, this approach is limited to non-centrosymmetric materials^{11,13,14,15,16} magnetically biased near the antiferromagnet–ferromagnet transition. Here, we demonstrate control of the magnetic properties of both monolayer and bilayer CrI₃ by electrostatic doping using CrI₃–graphene vertical heterostructures. In monolayer CrI₃, doping significantly modifies the saturation magnetization, coercive force and Curie temperature, showing strengthened/weakened magnetic order with hole/electron doping. Remarkably, in bilayer CrI₃, the electron doping above ~2.5 × 10¹³ cm⁻² induces a transition from an antiferromagnetic to a ferromagnetic ground state in the absence of a magnetic field. The result reveals a strongly doping-dependent interlayer exchange coupling, which enables robust switching of magnetization in bilayer CrI₃ by small gate voltages.

二维材料的原子厚度提供了独特的机会来控制其电学¹和光学²特性，并通过静电掺杂来驱动电子相变³。二维磁性材料^{4、5、6、7、8、9、10}的发现为磁性的电控制和新功能装置¹¹的实现开辟了前景。最近的基于线性磁电效应的实验表明，通过电场^12可以控制双层CrI ₃中的磁序。但是，这种方法仅限于非中心对称材料^{11,13,14,15,16}在反铁磁-铁磁过渡附近磁偏。在这里，我们演示了通过使用CrI _3-石墨烯垂直异质结构进行静电掺杂来控制单层和双层CrI ₃的磁性能。在单层CrI _3中，掺杂显着改变了饱和磁化强度，矫顽力和居里温度，显示出随着空穴/电子掺杂而增强/减弱的磁序。值得注意的是，在双层CrI _3中，电子掺杂在〜2.5 ×10 ¹³  cm ^-2以上在没有磁场的情况下，会引起从反铁磁基态到铁磁基态的转变。结果揭示了强烈依赖掺杂的层间交换耦合，该耦合耦合使得能够通过小的栅极电压对双层CrI _3中的磁化强度进行鲁棒的切换。