Study on Magnetic Field-induced Magnetic Domain Dynamics Based on the Type and Thickness of the Underlayer in Co/Ni Nanowires

Abstract

In this study, we examined the magnetic field–induced dynamic change of magnetic domains in Co/Ni nanomagnetic wires, focusing on the effects of the underlayer type and thickness. Real-time domain observation was performed using a magneto-optic Kerr effect microscope, enabling the analysis of the changes in domain dynamics. The underlayers of Co/Ni magnetic wires were composed of Pt and Au with varying thicknesses. The Pt thickness was varied from 2.5 Å to 10 Å, and the thickness of Au was varied from 15 Å to 50 Å. First, the magnetization reversal of all samples exhibited a tendency of domain wall movement, with increasing coercivity for increasing underlayer thickness. Furthermore, by analyzing the domain wall velocity data for the magnetic field magnitude, it was confirmed that the domain wall movement in all samples could be effectively explained by the thermal activation model based on the domain wall creep motion. Additionally, we found that the magnetic field strength required magnetic domain wall movement increased with increasing underlayer thickness.