Field-driven and Spin-transfer-torque-driven Domain-Wall Dynamics: in Ferromagnetic Micro-/Nano- structures

The main topic of this book is to explore magnetic-field- and electric-current-driven domain-wall motion in thin-film-based magnetic microstructures. Conventional thin-film growth and microstructure fabrication techniques including electron-beam lithography and focused ion beam milling are used to fabricate nanometer-scale one-dimensional and two-dimensional magnetic structures that support magnetic domains (regions of different magnetization orientation separated by domain walls). A high-spatial resolution, high-temporal resolution technique for measuring the field- or current- driven dynamics of the domain walls, based on the magneto-optic Kerr effect, is developed and used to study the wall dynamics. Domain-wall motion driven by (spin-polarized) electric current is studied in nano-scale thin-film based wires. The experiments address issues pertaining to the basic mechanisms responsible for current-driven domain-wall motion, which are believed to be the adiabatic spin-torque mechanism and non-adiabatic mechanisms.