Direct observation of domain wall scattering in patterned Ni80Fe20 and Ni nanowires by current-voltage measurements.

We present measurements of domain wall resistivity, pinned by nanoconstrictions in single layer ferromagnetic wires of Ni80Fe20 and Ni. Unpinning domain walls from the constriction by current-induced switching allows for an unambiguous measurement of their resistivity changes, namely, 1.7% in Ni80Fe20 and 1.82% in Ni and both positive, which supports the theory of spin-dependent impurity scattering. By deriving an empirical relation for the various constriction widths, the large percentage changes of resistivity in ballistic nanocontacts are reproduced, showing a correlation between domain wall magnetoresistance and ballistic magnetoresistance.