Static and Dynamic Properties of Soft Ferromagnetic Materials Useful for Spintronic Devices

Abstract

In-depth understanding of static and dynamic properties of magnetic materials are important for enhancing the performance of magnetic memory devices. In particular, for the development of low power consumption-based racetrack memory, it is important to select suitable material parameters and geometry of the magnetic nanotrack. One of the crucial requirements for next generation racetrack memory is to achieve large velocity of chiral Domain Wall (DW) or skyrmion under the influence of spin transfer torque (STT). This thesis investigates on various magnetization dynamics mechanisms involved in the control of a skyrmion motion from a DW pair in a typical junction geometry composed of narrow and a wider nanotrack. Using micromagnetic simulation, we investigate the influence of two/three narrow nanochannels on the DW to skyrmion conversion and its dynamics. Importantly, we find that the separation between narrow nanochannel plays crucial role in governing the velocity and trajectory of the skyrmion dynamics in addition to and#945; and and#946; parameters. Further, our results also reveal that by means of increasing the number of narrow nanochannel, we can fine tune the skyrmion dynamics suitably by varying the separation lengths between nanochannels by either symmetric or asymmetrically. We show the DW pair to skyrmion conversion dynamics with the help of various energy profile evolution and the role of different forces that facilitates the conversion process. We found that the increase or decrease in the total energy value depends on the formation of skyrmion or fractional skyrmions. Overall, the understanding based on the variations in the energy profile and the evolution of topological charge during the conversion of the skyrmions, fractional skyrmions, and annihilated DWs are essential for designing an energy-efficient RM device newline