  The stochasticity of domain wall (DW) motion in magnetic nanowires has been
probed by measuring slow fluctuations, or noise, in electrical resistance at
small magnetic fields. By controlled injection of DWs into isolated cylindrical
nanowires of nickel, we have been able to track the motion of the DWs between
the electrical leads by discrete steps in the resistance. Closer inspection of
the time-dependence of noise reveals a diffusive random walk of the DWs with an
universal kinetic exponent. Our experiments outline a method with which
electrical resistance is able to detect the kinetic state of the DWs inside the
nanowires, which can be useful in DW-based memory designs.
