Uniaxial Strain-ModulatedElectronic Structure, MagneticProperties, and Curie Temperature of Monolayer MnOX (X = F/Cl/Br)

The emergence of two-dimensional intrinsic ferromagnetic materials and their unique advantages in the fields of electronics, sensing, and storage have attracted widespread attention. However, their practical applications are limited by their low magnetic anisotropy energy (MAE) and Curie temperature (<i>T</i>_C). Here, through first-principles calculations, we predict that the electronic structure, MAE, and Curie temperature of MnOX (X = F/Cl/Br) can be effectively controlled by applying strain along the <i>b</i>-axis. The results show that after applying a <i>b</i>-axis strain of −8 to 8%, monolayer MnOX remains in the ferromagnetic state. Moreover, the application of such a strain can induce a transition between semiconducting and half-metallic properties. Furthermore, in monolayer MnOBr, a compressive strain of 2.15% along the <i>b</i>-axis reverses the EMA direction from in-plane to out-of-plane. Interestingly, in monolayer MnOBr, a compressive strain of 8% along the <i>b</i>-axis increases the MAE along the (100)/(010) direction from 0.269/–0.642 to 0.568/1.121 meV/u.c., and the <i>T</i>_C remains high (477 K). Based on second-order perturbation theory, the positive contributions of the Br atomic matrix elements (<i>p</i>_<i>x</i> and <i>p</i>_<i>y</i>) play a dominant role in the MAE changes of MnOBr. The computational results demonstrate that monolayer MnOX has great potential for applications in next-generation spintronic devices.