Magnetic properties and coercivity mechanism of MnGa films

MnGa compounds possess several fascinating and useful properties, such as a large magnetocrys-talline anisotropy K_u, a high spin polarization P, a high Curie temperature T_C and a flexible magnetization M. These results suggest that MnGa compounds are of potential candidates for spin-transfer-torque and rare-earth-free permanent magnet applications. There are two most interesting tetragonal phases, D0₂₂-Mn₃Ga and L1₀-MnGa, among magnetically ordered phases of Mn-Ga binary alloys. Compared to the bulk-MnGa materials, it is easier to achieve a high coercivity (H_C) in MnGa films, which is probably attributed to the suitable grain size and orientation. It is valuable to clarify the origin of magnetic properties of MnGa films, which are affected by different experimental conditions. In the present study, the D0₂₂-type and L1₀-type MnGa films with different thickness (10-50 nm) and underlayers are prepared on three kinds of substrates by magnetron sputtering. The magnetic properties of MnGa films are studied and the coecivity mechanism is discussed.