Measurements of nanoscale domain wall flexing in a ferromagnetic thin film

We use the high spatial sensitivity of the anomalous Hall effect in the ferromagnetic semiconductor Ga_1-xMn_xAs, combined with the magneto-optical Kerr effect, to probe the nanoscale elastic flexing behavior of a single magnetic domain wall in a ferromagnetic thin film. Our technique allows position sensitive characterization of the pinning site density, which we estimate to be ∼1014cm^-3. Analysis of single site depinning events and their temperature dependence yields estimates of pinning site forces (10 pN range) as well as the thermal deactivation energy. Our data provide evidence for a much higher intrinsic domain wall mobility for flexing than previously observed in optically probed μm scale measurements.