Influence of Different Asymmetry Level on Vortex Annihilation Field in Permalloy Nano Dots
Deng-Shiang Shiu1*, Kuo-Ming Wu1, Chao-Hsien Huang1, Kao-Fan Lai1, Jong-Ching Wu1, Lance Horng1
1Physics, National Changhua University of Education, Changhua, Taiwan
* presenting author:Deng-Shiang Shiu,
We study the asymmetry effect on magnetic dots to control magnetic domain in order to employ them in magnetic sensors and logic devices. Therefore, we fabricate samples in the form of series of submicron-scaled Py dots by e-beam lithography and magnetron-sputtering to investigate the geometrical asymmetry effects on vortex annihilation in the devices. By introducing an one-side-flat asymmetric shape into the circular magnetic disks, the original degenerate signals of vortex annihilation for different chiralities are separated into two different trajectories, where asymmetry level is quantified by an excised angle. The separation of annihilation fields for clockwise and counter-clockwise vortexes emerges as a function of the excised angle. The asymmetric influence on the separation of annihilation fields is discussed from the view of disk aspect ratio and flat boundary effect. In order to make comparison of experimental results with numerical simulations, we employ micromagnetic simulation software – LLG simulator model the behaviour of the domain states. We will employ this result of simulation to examine the variation of magnetic energies for different domain states.

Keywords: Magnetic vortex , Asymmetry magnetic dot, Asymmetry magnetic disk, Magnetic skyrmion