Magnetic force microscope (MFM) is a type of scanning probe microscope (SPM) that detects and images the gradient of the stray magnetic field of the observed sample. Therefore, the magnetic domain image is greatly affected by the surface morphology of the probe and the magnetic properties of the coated magnetic thin film. If the strong stray magnetic field for the permanent magnet material disturbs the magnetization of the magnetic probe, accurate observation of the magnetic domain structure is difficult. L10 ordered FePt alloy with high uniaxial magnetocrystalline anisotropyis thought to be an candidate probe material because of its high corrosion resistance and high coercivity1. It has also reported that the orientation of the FePt layer can be controlled by introducing MgO layer2. However, there are only a few reports of magnetic domain images observed by MFM probes using FePt film. In this study, the orientation of the FePt layer was controlled by using a MgO under layer with varying film thickness and element additions in order to observe high-resolution magnetic domain images.
The FePt coated probes were prepared using an ultra-high vacuum magnetron sputtering system. A MgO buffer layer was deposited on Si cantilever and Si substrate at room temperature (R.T.). Then, FePt was deposited at a substrate temperature Ts of 873 K and they were annealed at 973 K. The surface morphology of the probes was observed by scanning electron microscope (SEM). The crystal structure was evaluated by X-ray diffraction (XRD), and the magnetic properties weremeasured usinga superconducting quantum interference device (SQUID) magnetometer.
From XRD patterns, the fundamental (002) and the superlattice (001) peaks from L10 ordered FePt phase have been clearly observed atthe FePt probe by the introduction of MgO buffer layer, and a clear magnetic domain image was observed. However, when a Cu-doped MgO layer was used, the peak intensity from the L10ordered FePt phase increased and a magnetic domain image with even higher resolution was obtained. High-resolution mechanism will be discussed at the conference.