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 1000nm. 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 800nm. 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.

Effect of the Dot Separation on the Switching Behavior of Ni-Fe Elliptical Dot Arrays

“…Furthermore, in order to verify the effect on the dipole-dipole interaction between the adjacent dots in the 10-nm-thick Ni-Fe elliptical dot arrays with different distance, we investigated the details of the magnetization process in these dots using MFS-MFM, which can directly observe the precise magnetic state in an interest point within a single dot or a single nanowire at room temperature [9], [10]. Fig.…”

“…Additionally, the effect on the dipole-dipole interaction between the adjacent dots was measured by our proposed measurement method, namely, 'magnetic field sweeping (MFS)-MFM' [9], [10]. The detail of MFS-MFM was described in [9], [10]. Fig.…”

Local Probing of Magnetization Reversal in Ni–Fe Elliptical Dots With Variable Geometry

“…Recently, we have proposed a new magnetization measurement method, the magnetic field sweeping (MFS)-magnetic force microscopy (MFM) [9]- [11], which uses an MFM tip as a detector while the magnetic filed is swept. In MFS-MFM, the precise magnetic state of a local point in a single magnetic dot or a single magnetic nanowire can be directly observed at room temperature within one minute.…”

“…In MFS-MFM, the precise magnetic state of a local point in a single magnetic dot or a single magnetic nanowire can be directly observed at room temperature within one minute. Until now, we have successfully applied MFS-MFM to study the detailed magnetization reversal in a circular dot and the effect on the dipole-dipole interaction between the adjacent elliptical dots [9], [11]. We have also observed the domain wall trapping in an Ni constrictive structure and found the dominant contribution to the magnetization reversal process in an Ni-Fe nanowire with various thicknesses and sizes [10], [11].…”

“…Until now, we have successfully applied MFS-MFM to study the detailed magnetization reversal in a circular dot and the effect on the dipole-dipole interaction between the adjacent elliptical dots [9], [11]. We have also observed the domain wall trapping in an Ni constrictive structure and found the dominant contribution to the magnetization reversal process in an Ni-Fe nanowire with various thicknesses and sizes [10], [11]. In this paper, we report, using MFS-MFM, a detailed magnetization reversal in a single Ni-Fe elliptical dot with several dot sizes.…”