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 XBr2, XI2, 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 MnBr2 is most stable in the ferromagnetic phase, while the other compounds favor antiferromagnetic ordering. The inclusion of the effective Coulomb screening potential (Ueff) 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 CoI2—while MnBr2, CoBr2, and CoI2 exhibit half-metallicity in the ferrimagnetic phase. In the antiferromagnetic phase, MnBr2, MnI2, 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. © The Author(s) 2025.