Gate-tunable room-temperature ferromagnetism in two-dimensional FeGeTe.

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.