  Despite the relevance of current-induced magnetic domain wall (DW) motion for
new spintronics applications, the exact details of the current-domain wall
interaction are not yet understood. A property intimately related to this
interaction is the intrinsic DW resistivity. Here, we investigate
experimentally how the resistivity inside a DW depends on the wall width D,
which is tuned using focused ion beam irradiation of Pt/Co/Pt strips. We
observe the nucleation of individual DWs with Kerr microscopy, and measure
resistance changes in real-time. A 1/D^2 dependence of DW resistivity is found,
compatible with Levy-Zhang theory. Also quantitative agreement with theory is
found by taking full account of the current flowing through each individual
layer inside the multilayer stack.
