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 KTiOPO4; quantum ferroelectric SrTi¹⁸O3; relaxor ferroelectric Sr0.61Ba0.39Nb2O6 (SBN); ultrathin ferromagnetic multilayers Pt/Co/Pt; and discontinuous magnetic metal-insulator multilayers [Co80Fe20/Al2O3]10 (DMIM) with ac susceptibility, , 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, . 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 Tc.