Abstract
The operating performance of a domain wall-based magnetic device relies on the controlled motion of the domain walls within the ferromagnetic nanowires. Here, we report on the dynamics of coupled Néel domain wall in perpendicular magnetic anisotropy (PMA) nanowires via micromagnetic simulations. The coupled Néel domain wall is obtained in a sandwich structure, where two PMA nanowires that are separated by an insulating layer are stacked vertically. Under the application of high current density, we found that the Walker breakdown phenomenon is suppressed in the sandwich structure. Consequently, the coupled Néel domain wall of the sandwich structure is able to move faster as compared to individual domain walls in a single PMA nanowire.
Highlights
The operating performance of a domain wall-based magnetic device relies on the controlled motion of the domain walls within the ferromagnetic nanowires
When current is applied to the middle nanowire, the behaviour of the three-nanowire system becomes similar to that of the two-nanowire system; i.e. the three domain wall (DW) are able to move as a group when the applied current density is increased beyond a critical value, as shown in the first image of Fig. 4 (b)
We have shown that coupled DWs in perpendicular magnetic anisotropy (PMA) sandwich structure are able to form the Neel configuration under zero external field or current
Summary
The operating performance of a domain wall-based magnetic device relies on the controlled motion of the domain walls within the ferromagnetic nanowires. O ne of the key factors that determines the performance of magnetic domain wall (DW)-based devices[1,2] is the ability to drive the DWs as fast as possible upon the application of current Materials such as permalloy (Ni80Fe20) with in-plane magnetic anisotropy are considered, as these materials possess high anisotropy magnetoresistance for the ease of DW detection[3]. When high current density is applied to drive the DW, the magnetization within the DW is tilted continuously, which causes the DW shape to change periodically This phenomenon is known as the Walker breakdown, where the DW continuously switches between Bloch and Neel configurations, as shown in Fig. 1 (a)[7,8]. Difference between the Bloch state and the Neel state is close to zero[11,17], which explains why the single DW appears to move linearly even when the applied current density is already in the Walker breakdown regime
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