Domain Wall Dynamics in Nanoscale Structures

Domain walls, the boundaries between regions of uniform magnetization, are the basis for various “spintronic” devices that utilize the magnetic moments, or spins, of electrons. With recent advances in lithographical techniques, domain walls can be confined and controlled as quasi-one-dimensional entities within submicron-wide magnetic tracks. Viable applications for such domain wall spintronic devices include memory storage, logic operations, and biomedicine. This work focuses on the fundamental physics of domain wall motion, which are governed by magnetic field, electric current, and temperature. In particular, submicron-wide thin film strips with out-of-plane magnetization are fabricated, which are promising device platforms because of the high spin-transfer efficiency for domain wall motion. We characterize the dynamics of domain walls within these patterned strips, both in the slow thermally activated regime and rapid viscous flow regime, using our high-resolution, high-bandwidth magneto-optical Kerr effect (MOKE) system.