Domain-wall dynamics driven by short pulses along thin ferromagnetic strips: Micromagnetic simulations and analytical description

Micromagnetic simulations are used to describe the domain-wall dynamics along thin ferromagnetic strips driven by short pulses of magnetic field or electrical current with sinusoidal shape. For perfect strips without pinning centers, the net displacement of the domain wall is proportional both to the amplitude and the duration of the field pulse. A similar behavior is observed under current pulses if some nonadiabatic corrections are taken into account. On the contrary, the net displacement is null in the perfect adiabatic case. The domain-wall dynamics driven by these pulses is also characterized for strips which contain a single constriction, which acts as pinning site for the wall. The results reveal that an initially pinned domain wall can be eventually expelled far away from the constriction but if the maximum displacement does not surpass a given threshold the domain-wall experiences an attractive force which pushes it again toward the initial pinning site. Finally, the analysis of the domain wall jumps between two pinning sites is carried out both at zero and at room temperature for several separations between them. The simulations point out that the jumps can be achieved by means of short field or current pulses in the subnanosecond regime, an observation which could find application for a fast and easily controlled writing mechanism for future magnetic random access memory devices based on a pinned domain wall.