On the Possible Magnetic Properties of Ultrathin Mn₂GaC Films on Al₂O₃ Substrates

The possibility of growth of thin Mn₂GaC MAX phase films on Al₂O₃ substrates with various orientations and their magnetic properties have been studied. The most favorable orientation relationships and interface planes in the Mn₂GaC//Al₂O₃ system, which indicate the possibility of growth on C-face (0001), S-face $(01\bar {1}\bar {1})$, N‑face $(11\bar {2}\bar {3})$, and R-face $(0\bar {1}1\bar {2})$ sapphire substrates, have been predicted within a geometric approach. Using the electron density functional method, the possible magnetic properties of continuous ultrathin Mn₂GaC films have been calculated under the condition of conservation of uniform expansions/compressions of the MAX phase lattice, which are induced by growth on the predicted substrates. The effect of the deformation of the Mn₂GaC lattice on magnetic ordering and magnetic moments has been determined, and the possibility of a transition from an antiferromagnetic to a ferromagnetic state under the action of external magnetic fields has been evaluated. It has been shown that the growth of the ferromagnetic film of the Mn₂GaC MAX phase is the most probable on the Al₂O₃ (0001), Al₂O₃$(11\bar {2}\bar {3})$, and Al₂O₃$(0\bar {1}1\bar {2})$ substrates.