Abstract
Abstract
We conducted a thorough experimental and numerical study of the micromagnetic properties of Permalloy (Ni80Fe20) microdisks exhibiting target domain structures at remanence. Vortex configurations are quite common in such microdisks and correspond to an in-plane (IP) flux closure configuration of cylindrical symmetry with an out-of-plane (OOP) magnetized core. In contrast, target domain configuration are observed in thicker microdisks and are characterized by a vortex configuration of the IP component of the magnetization superposed to an OOP component of magnetization which oscillates as a function of the distance to the microdisk center resulting in the formation of concentric domains. The ratio of the OOP oscillatory component of the magnetization to the IP vortex one increases with the thickness of the microdisk. Hysteresis loops were measured under IP and OOP field. The results at remanence and under magnetic field could be interpreted by micromagnetic simulations in which the microdisks were described as an assembly of partially coupled columns representing the granular nanostructure of the films from which the microdisks were patterned. Quite original magnetization processes take place in these microdisks exhibiting target domain remanent configuration. These include in particular entire flipping of the domain configuration and annihilation/creation of ring domains.
Funder
H2020 European Institute of Innovation and Technology
Subject
Surfaces, Coatings and Films,Acoustics and Ultrasonics,Condensed Matter Physics,Electronic, Optical and Magnetic Materials