Studies of Mn-based permanent magnetic materials MnX(X=Al, Ga)

Since Mn atoms in the system of Mn-based materials can have large magnetic anisotropy and high magnetic moments (almost twice as high as Fe atoms in pure Fe metal), ternary or quaternary Mn-based compounds show potential as hard magnetic materials with high performance and medium price[1-3]. However, the knowledge of the magnetic moment formation and the mechanism of the magnetic coupling between Mn moments in Mn-based materials are very limited, preventing the exploitation of the large reservoir of ternary and quaternary Mn-based compounds in the search for novel magnetic materials. In the current study, the magnetic and structural properties of Mn-based intermetallic compounds MnX(X=Al, Ga) have been investigated, for the goal of searching novel Mn-based materials suited for permanent magnets. We successfully produced single-phase materials of MnAl and MnGa using different methods. MnAl and Mn-Ga show promising hard magnetic properties, and exhibit various magnetic behaviors including spin reorientation and exchange bias. The origin and modification of the magnetocrystalline anisotropy and ferromagnetism in these compounds have been explored.