Atomic-scale control of domain wall motion in pristine and defective Fe nanowires with Spin-Lattice Dynamics

Magnetic domain wall (DW) motion in nanowires (NWs) is highly sensitive to structural disorder, yet most simulation studies assume ideal crystalline geometries or impose defect effects phenomenologically. NWs inevitably include surface relaxation and contain lattice defects, and may also undergo mechanical deformation during fabrication or operation. In this work, we employ spin-lattice dynamics (SLD) simulations to investigate DW motion in iron NWs and to show that voids and plastic deformation can control DW mobility, enabling an atomistic description of the coupled evolution of spins and lattice degrees of freedom. We first analyze DW motion in crystalline Fe NWs and demonstrate that SLD reproduces analytical predictions for DW width and velocity across a range of magnetic fields, anisotropy values, and damping parameters, with deviations of less than 20%. We then extend the study to NW containing a nanoscale void and plastically deformed structures generated under compression. These large-scale simulations employ about 425,000 atoms/spins. The atomistic features, including voids, dislocations, and grain boundaries, lead to non-monotonic DW motion in a NW and fluctuations during propagation, which are governed by a heterogeneous magnetic energy landscape that varies with lattice disorder. These effects are difficult to capture by conventional micromagnetic approaches. This study highlights the critical role of atomic-scale defects in controlling DW mobility and demonstrates that spin-lattice dynamics is especially well suited for accurately describing magnetization dynamics in nanostructures. Our atomic results establish that defect-generated lattice disorder creates a heterogeneous magnetic-energy landscape that controls DW motion and is difficult to represent predictively within standard continuum models.