Domain wall creep in an Ising ultrathin magnetic film

We have studied the motion of a magnetic domain wall (MDW) driven by a magnetic field H in a 2D ultrathin Pt/Co/Pt film showing perpendicular anisotropy and quenched disorder. MDW velocity measurements down to the so called creep regime show that the average energy barrier scales as (1/H)(mu) with mu = 0.24 +/- 0.04 and that the correlation function along a MDW is governed by a wandering exponent zeta = 0.69 +/- 0.07, in very good agreement with theories giving mu = 0.25 and zeta = 2/3. This is the first direct measurement of the creep regime for a moving interface in a disordered medium.