Onset of hard magnetic MnGa thin film on glass substrate

Abstract

In this study, magnetic properties and microstructure of L10 MnGa thin films deposited at different substrate temperatures (Ts) were carried out in order to determine the onset of the hard magnetic MnGa phase onto glass substrate. The thickness of MnGa thin film was kept at 200 nm while the Ts was varied from room temperature (RT) to 600 °C. When the Ts was below 300 °C, only Mn phases with small grain size were observable. However, the further increase in Ts to 325 °C led to the appearance of L10 (111) peak indicating the presence of the hard magnetic phase in the film on the glass substrate. Also, the continuous rise in Ts enhanced the magnetic properties such as saturation magnetization (Ms) and coercivity (Hc). The crystal size of L10 MnGa phase and surface roughness of the film were also increased with the increase of Ts. The selected area diffraction pattern (SADP) of Transition Electron Microscopy (TEM) effectively identified that the coexistence of pure Mn and A1 MnGa phases were present at Ts < 300 °C and that the L10 MnGa started to appear at Ts = 325 °C while the completion of L10 MnGa phase was seen at Ts > 400 °C. The High-Resolution TEM (HRTEM) images revealed the lattice and amorphous regions present in the MnGa thin film at Ts = 325 °C. Nevertheless, an increase of Ts to 600 °C presented a wide range of L10 (111) lattice signifying the thin film is still in MnGa phase. The onset of hard magnetic L10 MnGa phase is found out to be at 325 °C.