Anomalous thickness dependence of Curie temperature in air-stable two-dimensional ferromagnetic 1T-CrTe2 grown by chemical vapor deposition

The discovery of ferromagnetic two-dimensional van der Waals materials has opened up opportunities to explore intriguing physics and to develop innovative spintronic devices. However, controllable synthesis of these 2D ferromagnets and enhancing their stability under ambient conditions remain challenging. Here, we report chemical vapor deposition growth of air-stable 2D metallic 1T-CrTe2 ultrathin crystals with controlled thickness. Their long-range ferromagnetic ordering is confirmed by a robust anomalous Hall effect, which has seldom been observed in other layered 2D materials grown by chemical vapor deposition. With reducing the thickness of 1T-CrTe2 from tens of nanometers to several nanometers, the easy axis changes from in-plane to out-of-plane. Monotonic increase of Curie temperature with the thickness decreasing from similar to 130.0 to similar to 7.6nm is observed. Theoretical calculations indicate that the weakening of the Coulomb screening in the two-dimensional limit plays a crucial role in the change of magnetic properties.

Automated summary

The discovery of air-stable 2D metallic 1T-CrTe2 ultrathin crystals with long-range ferromagnetic ordering through chemical vapor deposition has provided insights into the change of magnetic properties due to weakening of Coulomb screening in the two-dimensional limit. The study showed a monotonic increase of Curie temperature with decreasing thickness, and a shift of the easy axis from in-plane to out-of-plane as thickness is reduced. The robust anomalous Hall effect confirmed the ferromagnetic ordering in these materials, which is rarely observed in other layered 2D materials grown by chemical vapor deposition.