State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China.
Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
Nature. 2018 Nov;563(7729):94-99. doi: 10.1038/s41586-018-0626-9. Epub 2018 Oct 22.
Materials research has driven the development of modern nano-electronic devices. In particular, research in magnetic thin films has revolutionized the development of spintronic devices because identifying new magnetic materials is key to better device performance and design. Van der Waals crystals retain their chemical stability and structural integrity down to the monolayer and, being atomically thin, are readily tuned by various kinds of gate modulation. Recent experiments have demonstrated that it is possible to obtain two-dimensional ferromagnetic order in insulating CrGeTe (ref. ) and CrI (ref. ) at low temperatures. Here we develop a device fabrication technique and isolate monolayers from the layered metallic magnet FeGeTe to study magnetotransport. We find that the itinerant ferromagnetism persists in FeGeTe down to the monolayer with an out-of-plane magnetocrystalline anisotropy. The ferromagnetic transition temperature, T, is suppressed relative to the bulk T of 205 kelvin in pristine FeGeTe thin flakes. An ionic gate, however, raises T to room temperature, much higher than the bulk T. The gate-tunable room-temperature ferromagnetism in two-dimensional FeGeTe opens up opportunities for potential voltage-controlled magnetoelectronics based on atomically thin van der Waals crystals.
材料研究推动了现代纳米电子器件的发展。特别是，磁性薄膜的研究彻底改变了自旋电子器件的发展，因为确定新的磁性材料是提高器件性能和设计的关键。范德华晶体在单层时仍保持其化学稳定性和结构完整性，并且由于原子层厚度很薄，因此很容易通过各种栅极调制进行调整。最近的实验表明，在低温下有可能在绝缘的 CrGeTe（参考文献）和 CrI（参考文献）中获得二维铁磁有序。在这里，我们开发了一种器件制造技术，并从层状金属磁体 FeGeTe 中分离出单层来研究磁输运。我们发现，在面外磁各向异性的作用下，FeGeTe 中的巡游铁磁体在单层时仍然存在。与原始 FeGeTe 薄片中的 205 开尔文的体相 T 相比，铁磁转变温度 T 被抑制。然而，离子门可以将 T 提高到室温，远高于体相 T。二维 FeGeTe 的栅极可调谐室温铁磁性为基于原子层范德华晶体的潜在电压控制磁电子学开辟了机会。
