For materials with out-of-plane (OOP) magnetization, it has been proposed to engineer a DW ratchet 11 to move all DWs in the same direction along a loop by applying alternating fields, but again this entails delicate engineering and this approach does not work in the case of in-plane-magnetized structures.Īs an alternative method to manipulate DWs, current-induced DW motion due to the spin torque effect 12, 13, 14 allows for synchronous motion of multiple domains and DWs independent of the spin orientation in the domains and thus forms an alternative way to efficiently manipulate the magnetization configuration in potential novel devices. Suggested approaches using in-plane fields and local actuation of DWs lead to slow slip-stick motion and very complex device architecture 10, which has not been realized because of the complexity and is not deemed very useful for realistic devices. Moreover, it is difficult to generate the homogenous in-plane magnetic fields required for the DW motion in the most commonly used in-plane-magnetized permalloy nanowires owing to the lateral geometry of field-generating strip lines. However, the conventional approach of using external magnetic fields parallel to the spin orientation in the domains has been plagued by the seemingly insurmountable problem that the magnetic fields enlarge or shrink domains and eventually lead to a collapse of the domains 9. Magnetic field-driven DW motion is well established with high DW velocities 6, 7, 8 and allows for non-contact writing without electrical connections to the sample, making it very attractive for many applications. Recently, a broad range of devices based on domain wall (DW) motion has been proposed, including high-density data storage, logic and sensing devices 1, 2, 3, 4, 5.
By performing scanning transmission X-ray microscopy, we are able to experimentally demonstrate in-plane magnetized domain wall motion due to out-of-plane magnetic field pulses. Micromagnetic simulations suggest that synchronous permanent displacement of multiple magnetic walls can be achieved by using transverse domain walls with identical chirality combined with regular pinning sites and an asymmetric pulse. Here we demonstrate a radically different approach: we use out-of-plane magnetic field pulses to move in-plane domains, thus combining field-induced magnetization dynamics with the ability to move neighbouring domain walls in the same direction. As an alternative method, synchronous current-induced domain wall motion was studied, but the required high-current densities prevent widespread use in devices. The conventional approach using magnetic fields does not allow for the synchronous motion of multiple domains. Magnetic storage and logic devices based on magnetic domain wall motion rely on the precise and synchronous displacement of multiple domain walls.
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