Controlling magnetism by purely electrical means is a key challenge to better information technology¹. A variety of material systems, including ferromagnetic (FM) metals^2,3,4, FM semiconductors⁵, multiferroics^6,7,8 and magnetoelectric (ME) materials^9,10, have been explored for the electric-field control of magnetism. The recent discovery of two-dimensional (2D) van der Waals magnets^11,12 has opened a new door for the electrical control of magnetism at the nanometre scale through a van der Waals heterostructure device platform¹³. Here we demonstrate the control of magnetism in bilayer CrI₃, an antiferromagnetic (AFM) semiconductor in its ground state¹², by the application of small gate voltages in field-effect devices and the detection of magnetization using magnetic circular dichroism (MCD) microscopy. The applied electric field creates an interlayer potential difference, which results in a large linear ME effect, whose sign depends on the interlayer AFM order. We also achieve a complete and reversible electrical switching between the interlayer AFM and FM states in the vicinity of the interlayer spin-flip transition. The effect originates from the electric-field dependence of the interlayer exchange bias.

通过纯电动方式控制磁场是更好的信息技术的主要挑战¹。为了磁场的电场控制，已经探索了各种材料系统，包括铁磁（FM）金属^2、3、4，FM半导体⁵，多铁磁^6、7、8和磁电（ME）材料^9,10。二维（2D）范德华兹磁体^11,12的最新发现为范德华异质结构设备平台¹³纳米级的磁性电学控制打开了新的大门。在这里，我们演示了双层CrI ₃中磁性的控制，这是一种反铁磁（AFM）半导体处于基态^12的状态，方法是在场效应器件中施加较小的栅极电压，并使用磁圆二色性（MCD）显微镜检测磁化强度。施加的电场会产生层间电势差，这会导致较大的线性ME效应，其符号取决于层间AFM阶数。我们还实现了在层间自旋翻转转变附近的层间AFM和FM状态之间的完全可逆电切换。该效应源自层间交换偏压的电场依赖性。