Study of magnetic vortex spin wave mode in triangular structures

Abstract

As a kind of nanoscale magnetic structure, the magnetic vortex has the advantages of small size, easy integration, easy control, low driving current density, low heat loss, etc. Owing to its potential application value and research significance, it has received more and more attention since its discovery.The existence of the magnetic vortex is the result of the competition between the exchange energy and the magnetostatic energy in the system. The magnetization of magnetic vortex usually contains the in-plane part and the central region part, so it usually has dual properties of chirality and polarity. The chirality is related to the arrangement of the magnetization in the plane, which can be divided into clockwise direction and counterclockwise direction. Moreover, the polarities +1 and –1 respectively represent the magnetization in the central area of the magnetic vortex core along the +<i>z</i> axis and –<i>z</i> axis. On the one hand, the magnetic vortex can be used as an information carrier in the storage device by driving the polarity reversal, and has the advantages of fast reading and writing speed, easy erasing and rewriting. On the other hand, it is expected to be used in next-generation spintronic devices, such as spin nano-oscillators based on magnetic vortex, which can continuously output high-frequency microwave signals. To further enhance the applicability of magnetic vortex, the Dzyaloshinskii–Moriya interaction (DMI) is introduced into the system, with symmetry breaking or strong spin-orbit coupling, and its dynamic process can be regulated by changing the magnetic vortex structure. The DM effective field plays a role in forcing the adjacent magnetization to be along the perpendicular direction in the heterostructure system lacking interface inversion symmetry. Thus, the existence of DMI can make the in-plane magnetization oriented to the out-of-plane direction. In this work, the triangle-shape magnetic vortex structure is varied by changing the strength of DM effective field. The microwave magnetic fields are respectively applied along the in-plane direction and out-of-plane direction, and the eigenfrequencies are obtained by using fast Fourier transform. Next, we further explore the spin wave modes at different eigenfrequencies. Finally, we vary the intensity of DMI in the system to adjust different eigenfrequencies. These results open up possibilities for the development and application of magnetic vortex in spintronics.