High-Curie-temperature ferromagnetism in bilayer Cr I3 on bulk semiconducting substrates

Two-dimensional (2D) ferromagnetic (FM) semiconductors with high Curie temperature have long been pursued for electronic and spintronic applications. Here we provide a general strategy to achieve robust FM state in bilayer Cr I₃ of the monoclinic stacking, which intrinsically has interlayer antiferromagnetic (AFM) order and weak in-plane FM coupling. We showed that the proximity effect from bulk semiconducting substrates induces electronic doping and significantly increases the FM nearest-neighbor exchange for bilayer Cr I₃ , leading to the AFM-to-FM transition for the interlayer spin configuration as well as enhanced intralayer FM coupling. By first-principles calculations and Monte Carlo simulations, bulk and 2D semiconductors providing different interaction strengths from strong covalent bonding to weak van der Waals (vdW) interaction with Cr I₃ are compared to thoroughly address the substrate effect on magnetic behavior and Curie temperature of bilayer Cr I₃ . These theoretical results offer a facile route for direct synthesis of 2D ferromagnets on proper semiconducting substrates to achieve high Curie temperature for device implementation.