Developing Laser-Assisted Heating Magnetization Utilizing a Distributed External Magnetic Field for Magnetic MEMS

Self-demagnetizing fields in uniformly magnetized flat magnets limit the surface magnetic flux density and output power of magnetic microelectromechanical systems (MEMS). In laser-assisted heating magnetization (LAHM), the laser locally reduces the coercivity, and a uniform reverse magnetic field subsequently reverses the magnetization. LAHM was developed to produce fine multipole patterns and address these performance limitations. This study extends LAHM by superimposing a distributed external magnetic field tailored to the target pattern. The field is generated by a pre-patterned multipole master NdFeB magnet (Br= 1.30 T, Hcj= 2388 kA/m) placed on a uniform reverse-field source, which strengthens the local magnetizing field in the target areas and attenuates it elsewhere. Experiments employing 0.3-mm-thick NdFeB samples demonstrate that distributed-field LAHM increases the magnetization ratio by 10.8% and the peak-to-peak surface magnetic flux density by 54.2 mT compared with conventional uniform-field LAHM. These results indicate a potential route to higher-performance multipole magnets for MEMS applications.