Domain-wall-induced electromagnons in multiferroics

Abstract

Using an atomistic approach, we predict the emergence of hybrid quasiparticles, namely, domain-wall-induced electromagnons, that arise from dynamical couplings between magnons and optical phonons in systems possessing ferroelectric domain walls. These quasiparticles induce THz resonances in magnetoelectric responses and preferentially localize either near the domain walls or near the middle of domains. Such behavior is explained through dispersion analysis that allows us to track the emergent multidomain excitations back to single-domain magnetoelectric (ME) modes. The latter, scattered by a periodic array of domain walls, are shown to endow the domain-wall-induced electromagnons with a mixed localized mode and standing- or propagating-wave characters. Such features can be exploited to reach strikingly large ME conversion and design more reliable and ultrafast ME devices with less energy consumption and using, e.g., local probes.