Magnetic domain wall motion in nanoscale multiferroic devices under the combined action of magnetostriction, Rashba effect and dry-friction dissipation

Abstract

The one-dimensional propagation of magnetic domain walls in a ferromagnetic nanostrip is investigated analytically in the framework of the extended Landau-Lifshitz-Gilbert equation. In particular, this study focuses on the characterization of the domain wall motion in the presence of stresses induced by a piezoelectric actuator, Rashba spin-orbit-torque due to structural inversion asymmetry and dry-friction dissipation accounting for structural disorder into the crystal lattice. By adopting the formalism of travelling waves and using realistic assumptions on the parameters here involved, it has been possible to deduce an explicit analytical expression of the DW velocity in the steady regime. It is also proven that the depinning threshold and the Walker breakdown, representing the boundaries of such a dynamical regime, are both affected by the strength of magnetostriction, Rashba field and dry-friction. Moreover, it is observed that the Rashba effect can also modify the domain wall mobility as well as the direction of propagation. The results here obtained are in qualitative good agreement with recent numerical simulations and experimental observations.