High throughput study on magnetic ground states with Hubbard U corrections in transition metal dihalide monolayers

Abstract

We present a high throughput study of the magnetic ground states for 90 transition metal dihalide monolayers TMX₂ using density functional theory based on a collection of Hubbard U values. Stable geometrical phases between 2H and 1T are first determined. Spin-polarized calculations show that 50 out of 55 magnetic TMX₂ monolayers are energetically prone to the 1T phase. Further, the magnetic ground states are determined by considering four local spin models with respect to different U values. Interestingly, 23 out of 55 TMX₂ monolayers exhibit robust magnetic ground orderings which will not be changed by the U values. Among them, NiCl₂ with a magnetic moment of 2 μ_B is a ferromagnetic (FM) insulator, while the VX₂, MnX₂ (X = Cl, Br and I), PtCl₂ and CoI₂ monolayers have noncollinear antiferromagnetic (120°-AFM) ground states with a tiny in-plane magnetic anisotropic energy, indicating flexible magnetic orientation rotation. The exchange parameters for both robust FM and 120°-AFM systems are analyzed in detail with the Heisenberg model. Our high-throughput calculations give a systematic study of the electronic and magnetic properties of TMX₂ monolayers, and these two-dimensional materials with versatile magnetic behavior may have great potential for spintronic applications.