Current-induced domain wall motion with adiabatic and nonadiabatic spin torques in magnetic nanowires
Institute for Theoretical Physics, University of
Regensburg, 93040 Regensburg, Germany
2 Physics Department, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, P.R. China
Revised: 20 December 2010
Published online: 1 February 2011
We investigate current-driven domain wall (DW) propagation in magnetic nanowires in the framework of the modified Landau-Lifshitz-Gilbert equation with both adiabatic and nonadiabatic spin torque (AST and NAST) terms. By employing a simple analytical model, we can demonstrate the essential physics that any small current density can drive the DW motion along a uniaxial anisotropy nanowire even in absence of NAST, while a critical current density threshold is required due to intrinsic anisotropy pinning in a biaxial nanowire without NAST. The DW motion along the uniaxial wire corresponds to the asymptotical DW oscillation solution under high field/current in the biaxial wire case. The current-driven DW velocity weakly depends on the NAST parameter β in a uniaxial wire and it is similar to the β = α case (α: damping) in the biaxial wire. Apart from that, we discuss the rigid DW motion from both the energy and angular momentum viewpoints and point out some physical relations in between. We also propose an experimental scheme to measure the spin current polarization by combining both field- and current-driven DW motion in a usual flat (biaxial) nanowire.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2011