Mapping Domain Wall Pinning Locations in Magnetic Nanowires via X-Ray and Electron Transmission Correlative Microscopy

During a recent beamtime at MISTRAL (2023027482), we successfully demonstrated controlled domain wall motion in cylindrical nanowires along the Oersted field direction at a current density of 1010 A/m2, which is two orders of magnitude lower than previously reported values. This represents the first experimental evidence of domain wall motion along a controlled direction in cylindrical nanowires. These results were achieved for Permalloy nanowires with diameters above 200 nm and chemical notches. The 200 nm diameter allows the stabilization of azimuthal domains, which directly couple with the Oersted field induced by a current pulse. In addition to the intentional pinning sites (chemical notches), other regions of the NWs, indistinguishable from their surroundings by TXM, were found to act as pinning locations at such low driving currents. The aim of this study is to unambiguously identify the sources of domain wall pinning by performing correlative microscopy combining X-Ray Transmission magnetic imaging with Transmission Electron Microscopy on the same exact nanowires. This experiment will bring us one step closer to the potential use of these nanowires in domain-wall-based magnetic devices.