Surface defect detection of magnetic microwires by miniature rotatable robot inside SEM

Surface defect is regarded as one critical factor that affects magnetic properties of magnetic microwires. However, current imaging techniques only allow to observe samples from one fixed direction, and thereby most of surface defects on microwire cannot be detected. Herein, we firstly develop a miniature rotatable robot inside scanning electron microscopy (SEM) and propose a relevant control strategy to align the microwire onto the rotation axis of the robot. After that, the microwire is rotated continuously by 360º and all the surface defects on the microwire are observed from different directions successfully. Multidirectional observation results can be used to located heating inhomogeneity, which is the main cause of defects. Magnetic measurement results show that the effect of defects on domain wall (DW) should be considered in device design. This research provides the direct evidence for surface defects' distribution and effect, which can be adopted to provide guidance for improving magnetic wire's fabrication process and designing logic circuits made from those magnetic wires.