Observing the magnetization reversal processes and anisotropic effective damping of epitaxial FeSi/MgO (001)

Abstract

Epitaxial FeSi film on MgO (001) substrate was fabricated via a radio frequency magnetron sputtering technology. The epitaxial relationship of FeSi(001)/[110]//MgO(001)/[100] was characterized by crystal structure measurements and confirmed by in-plane biaxial magnetic anisotropy through vibrating sample magnetometer (VSM). By measuring Kerr magnetic hysteresis loops and recording the real-time magnetic domain images through surface magneto-optic Kerr effect (MOKE), two successive 90° domain wall displacement along easy axis and two discontinuous 90° domain wall displacement along hard axis were directly observed. Meanwhile, the difference of magnetic hysteresis loops obtained by VSM and MOKE devices were discussed. Furthermore, from the results of magnetic field sweeping ferromagnetic resonance measurements, it was found that FeSi film possesses an anisotropic effective damping constant of 0.0042 for easy axis direction and 0.0053 for hard axis direction, which was ascribed to the crystallographic defects induced two magnon scattering contributions.

Effect of substrate temperature on the structural, static and dynamic magnetic properties of FeSi/MgO(001) films

“…We consider that the uniaxial magnetic anisotropy is related to the symmetry breaking at the interface mainly due to interface strain effect from the variation in lattice mismatch. It should be mentioned that the ARM curve and M-H loops at T s = 600 • C are not shown, but can be found in [18].…”

“…For Single crystal or epitaxial soft films, such as (001)-oriented Fe [13], FeSi [14], La 0.67 Sr 0.33 MnO 3 [15] and Co-based Heusler alloys [16,17], have four-fold symmetric cubic magnetocrystalline anisotropy, which is closely dependent on the crystallographic direction. Nevertheless, the uniaxial anisotropy produced by interface effects coexists with the expected strong cubic magnetocrystalline anisotropy, which plays a crucial role in magnetization reversal and magnetic anisotropy [16][17][18]. When interface stressinduced uniaxial anisotropy is applied by an electric field to epitaxial films deposited on a ferroelectric substrate (i.e.…”

“…Compared with pure Fe films, Si-doped Fe x Si 1−x films are ideal candidates for studying static and dynamic magnetic properties due to their relatively low and adjustable magnetic anisotropy field [14,20,26]. Recently, we prepared epitaxial Fe 75 Si 25 (FeSi)/MgO(001) film at a substrate temperature (T s ) of 600 • C and reported the real-time magnetization reversal process and anisotropic effective damping constant [18]. This prompted us to prepare FeSi/MgO(001) films in amorphous and epitaxial states by setting an appropriate substrate temperature and to further investigate the effect of crystal structure on the static and dynamic magnetic properties of FeSi films.…”