Microstructures and magnetic domain structures of nano-granular CoPt-Al-O thin films are investigated by Lorentz microscopy and electron holography. It is found that the CoPt-based nanocrystalline phases are basically surrounded by the Al2 O3-based amorphous phases and the area of the Al2O3 -based amorphous phases increases with the increase in oxygen content. Typical mazy domains and domain walls like fishbone are observed in the Co45.8Pt18.6Al17.3O 18.3 and in localized area of the Co38.7Pt 15.6Al16.3O29.4, respectively, while no magnetic domain walls are observed in the Co34.4Pt 13.5Al15.63O36.5. With the increase in magnetic field, domain walls like fishbone start to disappear and the magnetic flux density increases in the Co38.7Pt15.6Al 16.3O29.4, indicating the mixed-phase state of ferromagnetic and superparamagnetic phases. In the Co34.4Pt 13.5Al15.6O36.5 of superparamagnetic state, the fluctuated lines of magnetic flux are considered to reflect the randomly magnetized distribution of CoPt-based single domain particles.
- Electron holography
- Lines of magnetic flux
- Magnetic domain structure
- Nano-granular thin film
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering