Investigation of vortex domain wall dynamics in permalloy wires with different geometry notches by MOKE microscopy

• Main Authors: Hung,Yun, 洪韻
• Other Authors: 洪連輝
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/r94u7x

碩士 === 國立彰化師範大學 === 物理學系 === 105 === We report on vortex domain wall dynamics pinning behavior created by different geometry notches in permalloy wires. The samples were probed experimentally using MOKE microscope. The pattern on samples is made by a injection pad for form a vortex and a Py wire for propagate a domain wall. The injection pad was set as a circular plate of 20 μm diameter and connected to a permalloy wire with width is 2 μm and length is 54 μm. By changing the cut edge of the notches which near the injection pad, with θ=15 °、30 °、45 °, and fixed one of the geometric notch then discussed the depth of notch. The results show that all samples, the injection field were determined by the magnetic configuration of injection pad and were irrelevant to geometry of notches and depths. In addition to the common head-to-head magnetic wall (HH-DW), we also explores the tail-to-tail wall (TT-DW). The results show that the depinning field is not simply directly related to the chirality of vortex wall. In the HH-DW part, HH-CW (clockwise), the pinning field is relatively lower than HH-CCW (counterclockwise). In the part of TT-DW, it is opposite to the HH-DW, and it is consistent with any of the different geometries or depths. The difference between HH-CW and HH-CCW, TT-CW and TT-CCW gradually decreases when the depth goes deeper. For the different geometries corresponding to the same depth, there is no significant change in depinning fields, and the depth is slightly positive correlation with it. In addition, three different geometric notches also shows that the pinning probability is increased with depth increased, until the depth ratio is about 0.6, and the pinning probability is close to 100%.