Doping-Driven Antiferromagnetic to Ferromagnetic Phase Transition in Tetragonal Cr 2 B 2 Monolayer

Novel two-dimensional (2D) tetragonal (tetra-) CrXB 2 (X = Mn, V) sheets are studied using density functional theory (DFT) with Monte Carlo (MC) simulations. Both, tetra- CrMnB 2 and tetra- CrVB 2 sheets exhibit metallic ferromagnetism with great stability at elevated temperatures. The magnetic moment for tetra- CrMnB 2 (1.63 mu (B) per unit cell) and tetra- CrVB 2 ( 0.53 mu (B) per unit cell) sheets are found to be far less than that of pure tetra- Cr 2 B 2 ( 6.02 mu (B) per unit cell). Interestingly, an antiferromagnetic-ferromagnetic (AFM-FM) transition occurs as a result of alloying the pure Cr 2 B 2 with Mn and V atoms. The tetra- CrMnB 2 exhibits a sizable magnetic anisotropy energy (MAE) of 136.25 mu eV per Mn - Cr atom, larger than that of tetra- CrVB 2 (17.5 mu eV per V - Cr atom), and both the sheets prefer out-of-plane magnetization. The MAE can be tuned via the application of an electric field for both, tetra- CrMnB 2 and tetra- CrVB 2 cases. MC simulations based on 2D Heisenberg model predict a Curie temperature ( T C ) of 140 and 20 K for tetra- CrMnB 2 and tetra- CrVB 2 sheets, respectively. These novel 2D sheets hold promise for controllable spintronic devices application.

Automated summary

Novel two-dimensional tetragonal CrXB2 (X = Mn, V) sheets exhibit metallic ferromagnetism and great stability at elevated temperatures. Alloying pure Cr2B2 with Mn and V atoms results in an antiferromagnetic-ferromagnetic (AFM-FM) transition.