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 $(1/H{)}^{\ensuremath{\mu}}$ with $\ensuremath{\mu}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.24\ifmmode\pm\else\textpm\fi{}0.04$ and that the correlation function along a MDW is governed by a wandering exponent $\ensuremath{\zeta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.69\ifmmode\pm\else\textpm\fi{}0.07$, in very good agreement with theories giving $\ensuremath{\mu}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.25$ and $\ensuremath{\zeta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2/3$. This is the first direct measurement of the creep regime for a moving interface in a disordered medium.