Electrical control of magnetism in van der Waals ferromagnetic semiconductors is an important step in creating novel spintronic devices, capable of processing and storing information, with these materials. For practical devices, electrical control at or near room temperature is sought, but most layered ferromagnetic semiconductors exhibit Curie temperatures below 100 K. Here, we show that electrostatic gating of thin chromium germanium telluride (Cr₂Ge₂Te₆) crystals can be used to modulate the magnetic phase transition and magnetic anisotropy of this layered ferromagnetic semiconductor and increase its Curie temperature. Using an electric double-layer transistor device, we observe ferromagnetism in the material at temperatures up to 200 K and find that its magnetic easy axis is in the in-plane direction, in contrast to the out-of-plane easy axis of undoped Cr₂Ge₂Te₆. Our analysis suggests that heavy doping promotes a double-exchange mechanism that is mediated by free carriers, which dominates over the superexchange mechanism of the original insulating state.

Van der Waals铁磁半导体中的磁性电学控制是使用这些材料创建能够处理和存储信息的新型自旋电子器件的重要一步。对于实际设备，寻求在室温或接近室温的情况下进行电控制，但是大多数层状铁磁半导体的居里温度都低于100K。在这里，我们证明了薄的碲化铬锗（Cr ₂ Ge ₂ Te ₆晶体可用于调节该层状铁磁半导体的磁相变和磁各向异性，并提高其居里温度。使用双电层晶体管器件，我们在高达200 K的温度下观察了材料中的铁磁性，发现其磁易轴位于平面内方向，与未掺杂Cr的平面外易轴相反₂ Ge ₂ Te ₆。我们的分析表明，重掺杂可促进由自由载流子介导的双交换机制，该机制主导着原始绝缘态的超交换机制。