The ac susceptibility of a superferromagnetic discontinuous multilayer $[\mathrm{C}{\mathrm{o}}_{\mathrm{80}}\mathrm{F}{\mathrm{e}}_{\mathrm{20}}(1.4\mathrm{n}\mathrm{m})/\mathrm{A}{\mathrm{l}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}(3\mathrm{n}\mathrm{m}){]}_{10}$ is measured as a function of temperature, frequency, and field amplitude and compared to static and dynamic hysteresis loops. Its properties are successfully mapped onto the predicted [T. Nattermann, V. Pokrovsky, and V. M. Vinokur, Phys. Rev. Lett. 87, 197005 (2001).] dynamical phase transitions, which link the relaxation, creep, sliding, and switching regimes of pinned domain walls.

• Received 9 April 2002

DOI:https://doi.org/10.1103/PhysRevLett.89.137203