Universal Domain Wall Dynamics in Disordered Ferroic Materials

The dynamics of driven domain walls (DWs) is studied in disordered uniaxial ferroic materials such as periodically poled ferroelectric KTiOPO 4 ; quantum ferroelectric SrTi 18 O 3 ; relaxor ferroelectric Sr 0.61 Ba 0.39 Nb 2 O 6 (SBN); ultrathin ferromagnetic multilayers Pt/Co/Pt; and discontinuous magnetic metal-insulator multilayers [Co 80 Fe 20 /Al 2 O 3 ] 10 (DMIM) with ac susceptibility, [Formula: see text], and domain imaging. Sideways creep and slide motion, well known from dc excitation, is mapped onto characteristic dynamic modes in the ac spectra or, more significantly, in Cole-Cole presentations, [Formula: see text]. Creep and slide are complemented by switching at high enough field amplitudes and by DW segmental relaxation at high enough frequencies. The dynamic relaxation-to-creep transition is well understood within scaling theory, whereas the crossover between the modes creep, slide, and switching is numerically modeled on the basis of the Edwards-Wilkinson equation of DW motion. Clear signatures of all dynamical modes are even found at fractal DWs in dipolarly controlled DMIMs and in polar nanoregions of random-field-controlled SBN above T c .