Electrically driven topological magnetic knots in BiFeO3 films

The fundamental nature of dynamic magnetoelectric coupling in multiferroics remains poorly understood. Despite these compelling static observations, its stability is governed by the convergence of the propagation direction ( k ) and the topology of the polarization structure, originating from the intertwining of π-disclinations. Strikingly, the knot exhibits synchronous propagation with ferroelectric domain walls under external electric fields, effectively preserving its topological integrity. Leveraging the topological nature of polarization order together with strong magnetoelectric coupling, a universal mechanism is manifested for the realization of nontrivial magnetic topological structures and their cooperative dynamics that should be operative across diverse topological materials. Our findings reveal a robust topology-mediated magnetoelectric dynamical mechanism, shedding light on the non-equilibrium physics of multiferroics and opening avenues for topological spintronics.