The Dynamics Of Magnetization In Ferromagnetic Nanowires With A Dzyaloshinshii-Moriya Interaction

Due to the widely application of storage devices and logic devices in real life, the interactions of transfer electron and domain wall movement have attracted the people’s attention. The spin-polarized current can induce the domain wall motion and distortion as same as the field-driven domain wall motion in ferrmagnetic nanowires. In this paper, we investigate domain wall motion and domain wall resonance driven by the spin-polarized current in ferrmagnetic nanowires with Dzyaloshinskii-Moriya interaction. The contents of paper are as following:Firstly, we introduce the dynamics theory of magnetization, and the basic theory of ferromagnetic resonance. Secondly, we introduce the basic model with stripe domain structures. Finally, the current induced domain wall motion and resonance are theoretically investigated in detail in ferromagnetic nanowires with a Dzyaloshinskii- Moriya interaction. Using the Landau-Lifshitz-Gilbert equation and energy density equations, an effective Newton’s equation is obtained analytically for a domain wall moving in one-dimensional potential and subject to a viscous friction and driving force. Then we obtain the solution of the Newton’s equation and the critical frequency and the speed of the moving domain wall. For the case of direct and alternating current, we get the critical dc and ac current density. At last, we discuss the effect of the critical dc current density, the resonance amplitude, the resonance frequency and the critical ac current density as a function of Dzyaloshinskii- Moriya interaction.