Theoretical prediction of two-dimensional ferromagnetic Mn 2 X 2 (X = As, Sb) with strain-controlled magnetocrystalline anisotropy.

Two-dimensional (2D) magnetic materials with large and tunable magnetocrystalline anisotropy (MCA) provide unique opportunities to develop various spintronic devices. We, herein, propose an experimentally feasible 2D material platform, Mn 2 X 2 (X = As, Sb), which is a family of intrinsic ferromagnet. Using first-principles calculations, we show that 2D Mn 2 X 2 (X = As, Sb) with a robust ferromagnetic ground state exhibits not only a large perpendicular magnetic anisotropy (PMA), but also significant strain-driven modulation behaviors under external biaxial strain. The analysis of the results demonstrates that the dominant contribution to the change of MCA of Mn 2 As 2 and Mn 2 Sb 2 primarily arises from the Mn and Sb atoms, respectively. Moreover, we reveal that the underlying origin is the competitive mechanism for the spin-orbit coupling (SOC) between different orbitals and spin channels. These findings indicate that 2D Mn 2 X 2 (X = As, Sb) provides a promising material platform for the next generation of ultra-low energy memory devices.