Micromagnetization patterning of sputtered NdFeB/Ta multilayered films utilizing laser assisted heating

A process for magnetizing small areas of a multilayered several micrometer thick NdFeB/Ta permanent magnet (PM) deposited by magnetron sputtering was developed. In this process, areas of the PM film heated by laser beam scanning were magnetized under an external DC magnetic field. First, by measuring the demagnetization curve at room temperature and 300 °C, the target temperature and external DC magnetic field were determined. These were found to be 300 °C and 0.8-0.9 T, respectively. Then, in order to satisfy these requirements, the heat conduction during laser heating was simulated, resulting in glass being chosen as the substrate material and, in addition, determining the laser beam scanning conditions. We also fabricated a DC magnetic field generator consisting of an array of bulk magnets which was designed using a magnetic field simulator. By adjusting the laser beam trajectories, magnetization patterns consisting of stripes with a width of 100 μm were experimentally generated in the 4.5 μm thick PM film. Agreement between the measured and simulated magnetic flux densities over the PM film was obtained. Furthermore, a 70 μm wide striped pattern, a 100 μm diameter dot pattern and a pattern consisting of a set of letters were also generated in the PM film. The desired magnetic field pattern could be successfully observed.