Sub-millimeter-Scale Growth of One-Unit-Cell-Thick Ferrimagnetic Cr₂S₃ Nanosheets

TLDR

Two‑dimensional magnetic materials are promising for spintronics because of their unique nanometer‑scale spin states, yet exfoliated monolayers are unstable in ambient air. This work seeks to synthesize high‑quality, air‑stable 2D magnetic materials. The authors achieve van der Waals epitaxial growth of one‑unit‑cell‑thick Cr₂S₃ by a simple chemical vapor deposition process. They obtain single‑crystal Cr₂S₃ domains up to 200 μm with a Néel temperature of 120 K, saturation magnetization of 65 μemu, coercivity of 1000 Oe, and p‑type transistor behavior (on/off > 10³), establishing monolayer Cr₂S₃ as a magnetic semiconductor for 2D spintronics and demonstrating a new vdW epitaxy route for nonlayered magnets.

Abstract

Two-dimensional (2D) magnetic materials provide an ideal platform for the application in spintronic devices due to their unique spin states in nanometer scale. However, recent research on the exfoliated monolayer magnetic materials suffers from the instability in ambient atmosphere, which needs extraordinary protection. Hence the controllable synthesis of 2D magnetic materials with good quality and stability should be addressed. Here we report for the first time the van der Waals (vdW) epitaxial growth of one-unit-cell-thick air-stable ferrimagnet Cr2S3 semiconductor via a facile chemical vapor deposition method. Single crystal Cr2S3 with the domain size reaching to 200 μm is achieved. Most importantly, we observe the as grown Cr2S3 with a Néel temperature (TN) of up to 120 K and a maximum saturation magnetic momentum of up to 65 μemu. As the temperature decreases, the samples show a transition from soft magnet to hard magnet with the highest coercivity of 1000 Oe. The one-unit-cell-thick Cr2S3 devices show a p-type transfer behavior with an on/off ratio over 103. Our work highlights Cr2S3 monolayer as an ideal magnetic semiconductor for 2D spintronic devices. The vdW epitaxy of nonlayered magnets introduces a new route for realizing magnetism in 2D limit and provides more application potential in the 2D spintronics.