WCl₃ monolayer: a first principles prediction of electronic and magnetic properties under an external electric field

This current study focuses on predicting the electronic and magnetic behaviors of WCl₃ monolayer when subjected to an external electric field. Unlike CrI₃, the WCl₃ monolayer displays a preference for an antiferromagnetic (AFM) ground state with an in-plane easy axis. This AFM state remains consistent across the entire spectrum (0–1 V/Å) of the external electric field. The indirect electronic band gap of the WCl₃ monolayer is predicted to be about 2.16 eV. Through our analysis, we’ve identified that the dominance of the valence band maximum and the conduction band minimum stems mainly from the \({d}_{{x}^{2}-{y}^{2}}\) $d_{x^2-y^2}$ orbital (52% contribution) and the \({d}_{{z}^{2}}\) $d_{z^2}$ orbital (97% contribution) respectively, attributed to the W element. The majority of electronic transitions related to the band gap arise due to these specific orbitals. Furthermore, the application of an external electric field can adjust the band gap to zero, prompting a transition from semiconductor to metal at an electric field intensity of E = 0.9 V/Å. Using mean field theory, we estimate the Neel temperature (T_N) of the AFM system to be approximately 356 K, a notably high value surpassing room temperature. Moreover, the application of an electric field demonstrates the potential to further elevate the Neel temperature, crucial for the functionality of high-temperature spintronic devices. Our comprehensive examination also delves into the magnetic anisotropy of the WCl₃ monolayer. The analysis of magnetic anisotropy energy (MAE) indicates that, contrary to the CrI₃ monolayer, the transition metal W significantly contributes to the system’s MAE, which is predicted to be −  \(3.44\text{ meV}/\text{W}\) $3.44\text{meV}/\text{W}$ . The magnetic easy axis aligns along the \(x\) $x$ direction (in-plane).