Enhanced controllability of domain-wall pinning by asymmetric control of domain-wall injection.

We investigate a control scheme for enhancing the controllability of domain-wall (DW) pinning on ferromagnetic devices using an interaction between magnetic charges distributed on a nanobar and at a notch, respectively. The scheme is realized at an artificial notch with a nanobar vertical to it on Permalloy nanowires with an asymmetrical pad. Injection fields for injecting the DWs from the asymmetrical pad to the nanowire show an asymmetrical dependence on the saturation angle for initializing the magnetization of the nanowire, and the injected DWs are pinned by the notch with the nanobar vertical to it. We have found that the landscape of the pinning potential energy experienced by the DWs depends on the magnetized direction of the nanobar and that its level is shifted by the injection field, leading to an increase or decrease in the depinning field with respect to the saturation angle. This is consistent with our estimation based on micromagnetic simulation.