Switching Behavior of Vortex State in Permalloy Asymmetric Nanoring

• Main Authors: Chia-Jung Hsu, 許嘉榕
• Other Authors: Lance Horng
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/63928297786696526529

碩士 === 國立彰化師範大學 === 光電科技研究所 === 101 === In this work, a method to control over the vortex state (flux-closure state) nucleation and annihilation field in asymmetric Permalloy (Py) rings are presented. By introducing an inner circle shifted from the center of outer circle by a shift length, samples of asymmetric Permalloy rings with different asymmetric ratios were fabricated by using E-beam lithography, sputtering, lift-off techniques. And We measured by focused magneto-optic Kerr effect magnetometry and OOMMF program to analyze the magnetic reversal behaviors, and the trend of experiment data agree well with simulation results. The vortex nucleation (Hn) and vortex annihilation (Han) fields, analyzed from the simulated and experimental hysteresis loops of 800 and 1000 nm outer diameters, have linear relations to the asymmetric ratio. It was observed that the nucleation field (Hn) and annihilation field (Han) both are proportional to shift length. And we investigate the influence of different inner diameter on magnetic reversal behavior. The both analyzed switching fields from experiment and simulation present a linear relation with the aspect ratio. This relation indicates that the Hn and Han of asymmetric ring arrays are mainly controlled by the shape anisotropy. It is observed that the switching behavior is in agreement with the simulated and experimental results.