First-Principles Calculations of the Spin-Dependent Electronic Structure and Strain Tunability in 2D Non-van der Waals Chromium Chalcogenides Cr₂X₃(X = S, Se, Te): Implications for Spintronics Applications

First-principles calculations are performed to study the electronic and magnetic properties of non-van der Waals (vdW) chromium chalcogenide Cr2X3 (X = S, Se, Te). Our results unveil their spin-dependent properties with strain tunability. Cr2Se3 is an intrinsic half-metal with a fully compensated ferrimagnetic (FCFiM) state. Cr2S3 is a bipolar magnetic semiconductor with an FCFiM state and half-semiconductor under a slight strain. Cr2Te3 is a conventional metal with a ferromagnetic (FM) state. Straining is feasible for this material to tune the band gap spin-selectively and induce magnetic phase transition. The interplay between inequivalent Cr sites under strains reveals that interlayer magnetic interaction mainly contributes to the system's magnetic configuration and favors the antiferromagnetic (AFM) state through direct exchange coupling if the spacing is smaller than 3 Å (responsible for both S and Se) but selects the FM state through superexchange-like interactions (responsible for Te) for longer spacing. While in-plane magnetic anisotropy is observed for S and Se, strong perpendicular magnetic anisotropy is dominant for Te. Our results will further stimulate studies of non-vdW materials and their potential for future spintronics applications.