Prediction of momentum dependent spin splitting in low-Z collinear and noncollinear antiferromagnets even without spin-orbit coupling*

The conventional way of creating spin splitting without external field entails spin orbit coupling (SOC). The latter requires heavy elements that lead to weak anion-cation bonds and undesirable defects. Pekar and Rashba [Zh. Eksp. Teor. Fiz. 47, 1927 (1964)] envisioned an alternative mechanism in antiferromaagnets (AFM) that would generate momentum dependent spin splitting. We identify the magnetic symmetry conditions that produce AFM prototypes having spin splitting even without external magnetic field and even when the SOC is set to zero.[Yuan, Wang, Luo, Rashba and Zunger. Physical Review B 102.1 (2020): 014422.] The resulting spin splitting in AFM is not restricted to noncentrosymmetric crystals, has a magnitude comparable to best known giant SOC spin splitting, and does not rely on SOC. Band structures of specific antiferromagnetic compounds for both collinear and noncollinear are worked out within DFT showing the effects. [Yuan, Wang, Luo, and Zunger. arXiv:2008.08532 (2020).] We envision that use of the current design principles to identify an optimal antiferromagnet with spin-split energy bands would be beneficial for spintronic applications without the burden of requiring compounds containing heavy elements.