Structural, Electronic and Optical Properties of Altermagnet Bulk MnBr₂

Spontaneous time-reversal symmetry breaking phases are highly desirable due to their unique physical characteristics, low-dissipation electronic and spin responses, and potential applications in information technology. Altermagnets are distinguished by their unique spin-splitting properties that are not governed by conventional exchange interactions but instead arise from an unconventional symmetry-driven mechanism. Herein, we study the structural, electronic, and optical properties of altermagnet MnBr2. The material has a rutile structure with lattice constants of a = b = 6.53315 & Aring;, and c = 3.99758 & Aring;. The antiferromagnetic state (AFM) was found to be more stable than the ferromagnetic state (FM) by calculating the energy difference between the FM and AFM states. To ensure thermodynamic stability, we calculated the formation energy, and the negative formation indicates that it is thermodynamically stable. We also calculated the phonon dispersion curve to ensure dynamic stability. The electronic band structure is calculated and found to exhibit the semiconducting nature of MnBr2. We found the band splitting of 120 meV, indicating the altermagnet nature of MnBr2. Furthermore, we investigated the optical parameters like the complex dielectric function, refractive index, absorption coefficient, reflectivity, and energy loss function in the energy range of 0-10 eV. Based on the obtained results, it can be suggested that MnBr2 may be a potential candidate for spintronic applications.