Exploring the potential of MnX (S, Sb) monolayers for antiferromagnetic spintronics: A theoretical investigation

In this study, we predicted new two-dimensional tetragonal structures of t-$Mn2X2$ (X = S, Sb) sheets on the basis of first-principles plane wave calculations within density functional theory with Hubbard U model. Stability tests such as phonon spectrum calculation and molecular dynamic simulations reveal that the 2D t-$Mn2X2$ structures are dynamically and thermally stable at least in room temperature. Our theoretical calculations have shown that t-$Mn2X2$ structures have two Raman active and seven infrared active modes. The t-$Mn2Sb2$ sheet exhibits metallic property, whereas t-$Mn2S2$ shows semiconducting property with a 0.68 eV indirect bandgap. Exploring of the favorable magnetic orientation calculations revealed that both 2D t-$Mn2X2$ structures prefer antiferromagnetic spin configuration. Estimated critical temperatures for the phase transition from antiferromagnetic spin order to paramagnetic case are 720 K and 545 K for t-$Mn2S2$ and t-$Mn2Sb2$⁠, respectively. These relatively high Néel temperatures and their suitable electronic properties for many applications clearly qualify that the 2D t-$Mn2X2$ sheets can be a good candidate for room temperature antiferromagnetic device applications.