Domain wall dynamics in magnetic nanowires

• Main Author: Toh, Jing Xiang
• Other Authors: Lew Wen Siang
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Science::Physics
• Online Access: http://hdl.handle.net/10356/59617
• Institution: Nanyang Technological University

The recent magnetic racetrack memory device proposed by IBM has garnered much interest due to its potential for high storage density and high read/write performance. It has potential to become a universal memory in the future. This project seeks to understand and study the domain wall dynamics that is crucial to the magnetic racetrack memory. The first part of this project study domain walls in perm alloy Cr/NiFe/Cr nanowires with in plane magnetic anisotropy. Domain walls were nucleated by magnetic field generated by current with pulse width and amplitude of 20 nanoseconds and 3.2 volts respectively. Domain walls propagation were induced by spin transfer torque from spin polarized current with pulse width and driving pulse amplitude of 50nanoseconds and -8Volts respectively. The second part of this project study domain walls in Ta/Pt/[Co/Ni]8/Ta nanowires with perpendicular magnetic anisotropy. The OOMMF software was used for simulations. For magnetic field induced domain wall propagation, it is observed that the magnetization switched within 50 nanoseconds and increasing the width of the nanowires will increase the speed of the domain walls. For current induced domain wall propagation, it is observed that the magnetization switched within 40 nanoseconds and increasing the width of the nanowires reduces the magnetization of the nanowires. Also, it was observed that the domain wall comprised of Neel and Bloch wall structures in an alternating configuration during the propagation of domain walls. The experimental nanowire sample fabricated for future studies is verified to have perpendicular magnetic anisotropy with a coercivity of 156.6mT obtained from the magnetic hysteresis loop.