Material research has been a major driving force in the development of modern nano-electronic devices. In particular, research in magnetic thin films has revolutionized the development of spintronic devices; identifying new magnetic materials is key to better device performance and new device paradigm. The advent of two-dimensional van der Waals crystals creates new possibilities. This family of materials retain their chemical stability and structural integrity down to monolayers 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 Cr2Ge2Te6 and CrI3 at low temperatures. Here, we developed a new device fabrication technique, and successfully isolated monolayers from layered metallic magnet Fe3GeTe2 for magnetotransport study. We found that the itinerant ferromagnetism persists in Fe3GeTe2 down to monolayer with an out-of-plane magnetocrystalline anisotropy. The ferromagnetic transition temperature, Tc, is suppressed in pristine Fe3GeTe2 thin flakes. An ionic gate, however, dramatically raises the Tc up to room temperature, significantly higher than the bulk Tc of 205 Kelvin. The gate-tunable room-temperature ferromagnetism in two-dimensional Fe3GeTe2 opens up opportunities for potential voltage-controlled magnetoelectronics based on atomically thin van der Waals crystals.
@article{arxiv.1803.02038,
title = {Gate-tunable Room-temperature Ferromagnetism in Two-dimensional Fe$_3$GeTe$_2$},
author = {Yujun Deng and Yijun Yu and Yichen Song and Jingzhao Zhang and Nai Zhou Wang and Yi Zheng Wu and Junyi Zhu and Jing Wang and Xian Hui Chen and Yuanbo Zhang},
journal= {arXiv preprint arXiv:1803.02038},
year = {2018}
}