Defect-driven antiferromagnetic domain walls in CuMnAs films

Antiferromagnetic (AF) materials offer a route to realising high-speed, high-density data storage devices that are robust against magnetic fields due to their intrinsic dynamics in the THz-regime and the lack magnetic stray fields. The key to functionality and efficiency is the control of AF domains and domain walls. Although AF domain structures are known to be sensitive to magnetoelastic effects, the microscopic interplay of crystalline defects, strain and magnetic ordering remains largely unknown. Here, we reveal, using photoemission electron microscopy combined with scanning x-ray diffraction microscopy and micromagnetic simulations, that the AF domain structure in CuMnAs thin films is dominated by nanoscale structural twin defects, which determine the location and orientation of 180° and 90° domain walls. The results emphasise the high sensitivity of the AF domain structure to the crystallographic nanostructure and provide a route to optimisng device performance.