Dynamics of localized modes in a composite multiferroic chain.

In a coupled ferroelectric-ferromagnetic system, i.e., a composite multiferroic, the propagation of magnetic or ferroelectric excitations across the whole structure is a key issue for applications. Of special interest is the dynamics of localized magnetic or ferroelectric modes (LM) across the ferroelectric-ferromagnetic interface, particularly when the LM's carrier frequency is in the band of the ferroelectric and in the band gap of the ferromagnet. For a proper choice of the system's parameters, we find that there is a threshold amplitude above which the interface becomes transparent and an in-band ferroelectric LM penetrates the ferromagnetic array. Below that threshold, the LM is fully reflected. Slightly below this transmission threshold, the addition of noise may lead to energy transmission, provided that the noise level is neither too low nor too high, an effect that resembles stochastic resonance. These findings represent an important step towards the application of ferroelectric and/or ferromagnetic LM-based logic.