The Exchange Stiffness Constant and Its Applications

Abstract

In magnetic heterojunction systems, the strong competition among Heisenberg exchange interaction, Dzyaloshinskii-Moriya (DM) interaction, and magnetocrystalline anisotropy can exhibit complex spin textures such as Skyrmions [1, 2], chiral magnetic domain walls (DWs) [3, 4], Bloch lines [6, 7], and so on. The interfacial DMI based on an inversion symmetry breaking structure has been widely investigated because of its various physical roles in the dynamics of the non-colinear spin structure. The exchange interaction is a purely quantum mechanical phenomenon on the ferromagnetic materials that only occurs between an atom spin and its nearest neighbor magnetic atoms. In this study, we introduce the determination of exchange stiffness constant on the ferromagnetic thin film and circular dots. The first method is using Brillouin light scattering (BLS). BLS is a versatile tool to investigate various magnetic properties such as the saturation magnetization, the perpendicular magnetic anisotropy energy, the exchange stiffness constant. The second way is using spin-wave eigenmode in the dish-shaped nanomagnet. Furthermore, we will discuss the magnetic skyrmion dynamics by applying gradient magnetic fields investigated by performing LLG simulations and Thiele approach. We described analytical and micromagnetic simulation studies of magnetic skyrmion dynamics in a 1-dimensional nanowire, force by magnetic field gradient along the z-direction while field gradient applied x-direction.