Study on the magnetization reversal process in a magnetic nanowire and a magnetic dot observed by magnetic field sweeping magnetic force microscopy measurements (invited)

Abstract

We have studied the details of the magnetization reversal process in Ni-Fe nanowires and dots using magnetic field sweeping (MFS)-magnetic force microscopy (MFM). All the points within the nanowire and the dot show important changes in phase (changes in stray field) including a hysteresis loop, a decrease and an increase in phase, as the magnetic field is varied. From these results, it is demonstrated that domain wall motion dominates the magnetization reversal process of a 10-nm -thick Ni-Fe nanowire with widths between 100 and 1000 nm. It is also demonstrated that the nucleation, the movement, and the annihilation of the vortex core can be directly observed in the magnetization reversal process of a 40-nm -thick Ni-Fe circular dot with diameters between 200 and 800 nm. Furthermore, it is found that, in the magnetization reversal process of a 10-nm -thick Ni-Fe elliptical dot with several major axial distances between adjacent dots, the magnetization between the adjacent dots magnetostatically couples as the major axial distance decreases. © 2008 American Institute of Physics.