Modulation of electronic and magnetic characteristics of Ni and Cr-based transition metal halide monolayers using strain engineering

This research delves into the magnetic properties of six transition metal dihalide monolayers including MX₂ (M = Ni, Cr X = Cl, Br, I) using density functional theory. We model the ground state of these samples using a simplified Heisenberg Hamiltonian, employing a supercell approach to derive the nearest and next-nearest exchange constants. Our results illuminate the influence of the electronic configuration of the transition metal element and the mass of the halogen atom on the magnetic ground state of the monolayers. Additionally, we provide an in-depth discussion on how strain impacts both the magnetic and electronic properties of the monolayers. Our study reveals that biaxial strain does not trigger a magnetic phase transition between ferromagnetic and antiferromagnetic states. Additionally, we observe that compressive strain elevates the Curie temperature and strengthens the exchange coupling. Conversely, these properties are diminished when the monolayer is subjected to tensile strain. The study enhances our understanding of the interplay between electronic structure and magnetic properties in transition metal dihalides, offering insights that could inform future material design and application in spintronic devices.