Intrinsic ferromagnetism in 2D h-CrC semiconductors with strong magnetic anisotropy and high Curie temperatures

Abstract

Two-dimensional (2D) intrinsic room-temperature ferromagnetic semiconductors are of great importance for the development of high-performance flexible electronic and spintronic nanodevices. In this work, we identify that the hexagonal chromium carbide (h-CrC) sheet is such a material using comprehensive density functional theory computations. Its thermodynamic structure and ferromagnetic ground state are both verified to be highly stable in an ambient environment. Apart from a large magnetic anisotropy with an easy out-of-plane magnetization axis, Monte Carlo simulations based on the classical Heisenberg model predict a high Curie temperature up to 555 K, well above room temperature for device applications. The ultrahigh carrier mobilities are recognized to be electron-dominated and feature directional migration. More importantly, the semiconducting and ferromagnetic nature of 2D h-CrC crystals remains rather robust and becomes even more excellent when subjected to different levels of biaxial strain. In particular, the moderate compressive strains not only activate the semiconducting h-CrC sheet into a half-metallic state but also strikingly enhance the Curie temperature and magnetic anisotropy energy. On the other hand, it is observed that the 2D h-CrC crystal begins to undergo an indirect-to-direct band gap transition at a 5% tensile strain. A feasible synthetic route is also proposed to realize the deposition of a h-CrC monolayer on the MoSe₂ substrate. The combination of these findings shows that the h-CrC monolayer is a promising candidate material for future practical applications in nanoscale electronics and spintronics.