Predictive study of Mn- and Co-based van der Waals compounds for spintronic and quantum applications

Abstract This study investigates the structural, electronic, and magnetic properties of XBr 2 , XI 2 , and XBrI (X = Mn, Co) compounds using density functional theory, incorporating spin–orbit coupling and the GGA + U framework. Cohesive and formation energy calculations reveal that MnBr 2 is most stable in the ferromagnetic phase, while the other compounds favor antiferromagnetic ordering. The inclusion of the effective Coulomb screening potential ( U eff ) enhances the localization of 3d orbitals, leading to increased magnetic moments. Electronic structure analyses show that most compounds transition to semiconducting behavior in the antiferromagnetic phase—except CoI 2 —while MnBr 2 , CoBr 2 , and CoI 2 exhibit half-metallicity in the ferrimagnetic phase. In the antiferromagnetic phase, MnBr 2 , MnI 2 , and MnBrI display topological Dirac-like points between the R and Γ points, suggesting the presence of massless fermions and enabling phenomena such as the quantum Hall effect and ultra-high carrier mobility. The computational results are consistent with available experimental data, highlighting the potential of Mn- and Co-based van der Waals compounds for spintronic and quantum applications.