Magnetization Of Magnetic Nanostructures And Magnetic Domains Move

High density storage and fast read/write technology has attracted considerable attention in the field of magnetic information recording, With the requirements of data storage density and data read speed increasing, Racetrack Memory technology is becoming a hot topic of research in the field of magnetic information recording. Racetrack actually consists of lots of magnetic nanowires. The data encoding of magnetic information recording is done with the magnetic domain on the magnetic nanowire, and read/write is achieved by spin-polarized current-driven domain wall motion, not as the traditional hard drives require disk rotation, which can save a lot of time and resources. And it is easy to implement device miniaturization. However, the technology of Current-driven domain wall motions is still in experimental stage and large-scale application requires a large number of empirical research. Then, the study of different magnetic properties and various dynamic regulation of the magnetic domain structure plays a vital role of literacy and stability of magnetic information. And it is the premise of the research of the spin polarized current-driven domain wall motion. In this paper, we have studied the magnetic properties and current-driven domain wall motion in the magnetic nanostripes by the Monte-Carlo simulation method and the new modified spin dynamics simulation method. The details are presented as follows.1. The magnetization reversal mechanism of the magnetic films system with the different magnetic anisotropy, exchange coupling, interface coupling, etc. has been simulated by Monte-Carlo method. The results show that the decrease of magnetic anisotropy is in favor of motion of domain walls, but is not conducive to consistent rotation. The interface coupling of both the ferromagnetic film and the antiferromagnetic film are helpful to the motion of domain walls while the antiferromagnetic film coupling is the more effective. Meantime, the evolution of the microscopic magnetic domain structures has been inspected intuitively while the system is in the process of magnetization.2. We studied the magnetic performance and magnetic domain structure of the magnetic thin film with the same size and lattice structure, but with different boundary shape by Monte-Carlo simulation method. The results indicated that the coercive field, magnetic moment and magnetic domain structure in the overall system regularly varied with the change of boundary shape, arid the boundary dipole interaction contributed to the enhancing of the coercive field, but it went against saturation magnetization. Although the coercive field is not strong, the particles with strong saturation magnetization have better performance. Therefore, we can control the magnetic properties by tailoring the boundary of the magnetic film.3. The effects of the current density, the interstripe spacing and the perpendicular anisotropy on the current-driven coupled vortex wall motions in two closely spaced nanostripes system are investigated by Landau-Lifshitz-Gilbert spin dynamics simulation. We show that the coupled vortex wall undergoes a spring-like oscillatory motion when current is applied to both nanostripes in opposite directions. The spring-like oscillatory motion may vanish, when the current density is larger than a critical value. The critical current density strongly depends on the interstripe spacing and the perpendicular anisotropy of the system. Moreover, diagrams of without oscillation, spring behavior and motionless upon the current and the interstripe spacing (the perpendicular anisotropy) are given.