Magnetic reversal for different shaped corners in sub-micron half-ring wires by mean phase analyses of magnetic force microscopy

In order to produce different types of domain wall or domain-wall pinning force on the corners of half-ring wires, three shapes of corners (rectangular, semi-circle and triangular) were fabricated. By means of real-time magnetic force microscopy (MFM) scanning, the hysteresis loops determined by mean phase values versus external magnetic fields can be obtained for the scanned regions at the corners. The samples with rectangular corners have the largest coercive field (∼75 Oe) at two sides among three corner structures. This behavior is consistent with that determined from the magnetoresistance (MR) measurements. Thus, from the method of MFM mean phase analysis, the magnetization reversal phenomena at local regions can be observed. Furthermore, the regions in the sample that trigger the magnetization reversal can also be detected.